TyroCity: Physics Notes

Nature and Propagation of Light

Physics XII Notes — Sat, 12 Jul 2014 05:41:42 +0000

Short

Differentiate between a plane wave front and a spherical wave front.
Which parameter of light does not change on refraction?
Define accommodation of eye and its near point.
What is Huygens principle?
When monochromatic light incidents on a surface, the reflected and refracted wave will have same frequency. Why?
State Huygens principle. Does it apply to sound waves in air?
What is a wave front?

Long

State and explain Huygens principle. Use the principle to show that a plane wave front incident obliquely on a plane mirror is reflected as a plane wave front so that angle of incidence is equal to the angle of reflection.
Prove the law of reflection of light using the wave theory?
Define Huygen’s principle and prove Snell’s law by the help of wave theory of light. State and explain Huygen’s principle. Use the principle to show that a plane wave front incident obliquely on a plane reflecting surface is reflected as a plane wave front so that the angle of incidence is equal to the angle of reflection.
Describe Michelson’s method for the determination of speed of light. Write advantages of the method over Foucault’s method.
State and explain Huygen’s principle. Use the principle to show that a p lane wave incident obliquely on a plane mirror is reflected as a plane wave so that the angle of incidence is equal to the angle of reflection.
Describe Foucault’s method for the determination of speed of light.

Wave Motion

Physics XII Notes — Sat, 12 Jul 2014 05:41:42 +0000

Wave motion

Short Questions

How are stationary waves formed?
If you are moving on the moon surface, can you hear the cracking sound behind you? Explain.
Do sound waves undergo reflection, refraction and polarization phenomena? Explain.
Which type of wave propagates in liquid, explain.
Longitudinal waves cannot be polarized. Why?
Distinguish between light waves and sound waves.

Long Questions

Use the principle of superposition of two waves to find the position of displacement of nodes and antinodes in standing waves?
State and explain the stationary waves?
Define progressive wave. Derive progressive wave equation.
What do you mean by progressive wave equation? Derive progressive wave equation in terms of its wave vector and displacement.
What the principle of superposition is as applied to wave motion? Discuss, the result of superposing two waves of equal amplitude and same frequency travelling in opposite direction.

Electromagnetic Induction

Physics XII Notes — Sat, 12 Jul 2014 05:41:42 +0000

Short Questions

What is Lenz’s law?
Mention two types of loss in a transformer.
Show that Lenz’s law is an example of conservation of energy.
Two closely would circular coils have the same number of turns, but one has twice the radius of the other. What is the ratio of self inductance’s of the two coils?
Why can`t a transformer be used to change the value of d.c. voltage?
What is eddy current? Write down its uses?
What are different power losses in a transformer? What measures do you take to minimize these losses?
Why can`t a transformer be used to step up or down the d.c. voltage?
A transformer cannot be used in do circuits, why?
State Faraday`s laws of electromagnetic induction.
A sheet of copper is placed between the poles of an electromagnet with the magnetic field perpendicular to the sheet. When it is pulled out, a considerable force is required, and the force required increases with speed, why?
Permanent magnets are made of steel while the core of transformer is made of soft iron. Why?
A student asserted that if a permanent magnet is dropped down a vertical copper pipe, it eventually reaches a terminal velocity even if there is no air resistance. Why should this be?
If a permanent magnet is dropped down a vertical copper pipe, it eventually reaches a terminal velocity even if there is no air resistance. Why should this be?
Describe the theory and working of an a.c. generator.

Long Questions

Obtain the expression for the emf induced in the conductor moving in a magnetic field.
State the laws of electromagnetic induction. Derive an expression for the emf induced in a conductor moving in a magnetic field.
Deduce an expression for induced emf in a coil rotating in a magnetic field.
State Lenz`s law and explain how this law leads to the conservation of energy principle.
State Faraday`s laws of electromagnetic induction. Deduce an expression for induced emf in a coil rotating in a magnetic field.
State and explain Faraday`s law of electromagnetic induction. Derive an expression for the induction a coil rotating in a uniform magnetic field.
State Faraday`s law of electromagnetic induction. Derive an expression for the induced in a straight conductor moving at right angle to the direction of a uniform magnetic field.
A metallic rod is moving in a magnetic field. Determine the emf induced across it.

Chemical Effect Of Current

Physics XII Notes — Sat, 12 Jul 2014 05:41:42 +0000

Short Questions

What is meant by Faraday’s Constant?
What is the function of copper sulphate used in Daniel cell?
Define one Faraday?
Distinguish between ionic and electronic conduction.

Long Questions

State and explain Faraday’s law of electrolysis. Hence, define Faraday’s Constant.
State the Faraday’s laws of electrolysis and verify the second laws.
State Faraday’s law of electrolysis. Discuss the experiment to verify them.

Interference

Physics XII Notes — Sat, 12 Jul 2014 05:41:42 +0000

Short Answer Questions

Can two independent sources of light produce interference?
Why have the two sources of light to be close to each other for the production of good interference pattern?
Distinguish between interference and diffraction. What do you understand by coherent sources?
In young’s double slit experiment, how is the fringe width altered if the separation between the slits is doubled and the distance between the slits and the screen is halved?
What are the conditions for sustained interference of light?
In Young’s double slit experiment, how is the fringe width altered if the separation between the slits is doubled and the distance between the slits and the screen is halved?
What do you understand by the coherent sources of light?

Long Answer Questions

Derive the fringe width from Young’s double slit experiment.
What do you understand by interference of light? Derive an expression for the fringe width in a Young’s double slits experiment.
Describe Young’s double slits experiment for the interference of light and show that widths of bright and dark fringes are the same.
Prove analytically that the bright and dark fringes in young’s double slit experiment are equally spaced.
Draw a clear ray diagram to illustrate the action of a compound microscope. Also derive an expression for its magnifying power.
Describe Young’s double slit experiment, if brief, for the measurement of wave=length of a monochromatic source of light.
Where is the near point of an eye for which a spectacle lens of power +2D is prescribed?

Electrical Circuits

Physics XII Notes — Sat, 12 Jul 2014 05:41:42 +0000

Short Questions

State Kirchhoff`s laws of circuits.
Why does voltmeter measures current more accurately than an ammeter?
What is Wheatstone bridge? Obtain the balanced condition for the bridge? Explain how resistance can be measured by a meter bridge?

Long Questions

What is a Wheatstone bridge? Using Kirchhoff`s law, derive the principle of Wheatstone bridge.
What is a potentiometer? Explain how you compare the emfs of two cells using a potentiometer.
Discuss the principle of potentiometer and use it to determine the internal resistance of a cell.
Discuss the principle of the potentiometer and use it to compare the emfs of two cells.
Explain the principle of the potentiometer. How is this used to measure the internal resistance of a cell?
State and explain Joule`s law of heating. Deduce an expression for the heat developed in a wire by the passage of an electric current?
What is potentiometer? How can you use it to measure internal resistance of a cell?
What is internal resistance of a cell? How can you measure the internal resistance of a cell by using potentiometer?
What is the principle of potentiometer? Describe a method to measure the internal resistance of a cell by using potentiometer.
What is Wheatstone bridge? Derive the principle of Wheatstone bridge using Kirchhoff`s Law.

Thermoelectric Effect

Physics XII Notes — Sat, 12 Jul 2014 05:41:42 +0000

Short Questions

What do you mean by Peltier`s effect?
What is thermoelectric emf?
Why is Sb-Bi thermocouple preferred to Fe-Cu thermocouple?
What are the factors on which the thermo emf produced in a thermocouple depends?
How is Seebeck effect different from Pektier effect? Explain.
How does thermo emf change in thermocouple when the temperature of the hot junction is changed?
What are the factor on which thermo-emf depend?
Define temperature of inversion. On what factors does it depend?
What do you mean by thermoelectric effect?
Does the thermo-electric effect obey the Law of conservation of energy? Explain.

Long Questions

What do you mean by Seebeck Effect? How thermoelectric e.m.f. does vary with the temperature?
What is Seebeck Effect? How does the emf of a thermocouple vary with temperature of the hot junction?
How does the thermo efm of a thermocouple vary with temperature of the hot junction?
What is thermoelectric effect? Discuss the variation of thermo-efm with the change in temperature of the hot junction.

Physics XII Questions

Physics XII Notes — Sat, 12 Jul 2014 05:41:42 +0000

Unit 1: Waves and Optics

Waves

Physical Optics

Unit 2: Electricity and magnetism

Current Electricity

Magnetic Field of current

Other topics

Free question test - Physics 12

Magnetic Properties of Materials

Physics XII Notes — Sat, 12 Jul 2014 05:41:42 +0000

Short Questions

What are magnetic domains?
What is angle of dip? How does it vary from the equator to the poles/
Define angle of dip and angle of declination at a place.
How does dip vary from place to place on earth`s surface?
Why does a bar magnet not retain its magnetism when it is method?
Why does a magnet lose its magnetism when heated to high temperature?
Above Curie temperature a ferromagnetic material becomes paramagnetic. Why?
What are the characteristics of a Ferro-magnetic substance?
A permanent magnet can be used to pick up a string of nails, tacks or paper clips, even though these are not magnets by themselves. How can this be?
A ferromagnetic substance becomes paramagnetic above Curie temperature. Explain why?

Long Questions

The angle of dip in Britain is greater than that in Kathmandu. Why?

DC Circuit

Physics XII Notes — Sat, 12 Jul 2014 05:41:42 +0000

Short Questions

An ammeter is always connected in series. Why?
Why do we use connecting wires made of copper?
What are the factors on which the resistance of a conductor depends?
Can the potential difference across a battery be greater than its emf?
Two bulbs of 60 W and 100 W are connected in series and this combination is connected across the mains. Which bulb will glow more brightly? Give reason.
You are given n wires each of resistance rΩ. What is the ratio of maximum to minimum resistance that can be obtained from these wires?
Is terminal p.d. always connected in parallel with the load resistance?
Two bulbs have the filament of the same length. If one is of 40 watt and the other 60 watt, which one has thicker filament?
Two bulbs have the filament of the same length. If one is of 40 watt and the other 60 watt, which one has thicker filament?
Why are alloys constantan and manganin used to make standard resistors?
A large number of free electrons are present in metals. Why is there no current in the absence of electric field across it?
Explain the significance of a shut with a diagram.
The element of heater is very hot while the wire carrying current are cold, why?
You are given 2 wires each of resistance R. What is the ratio of maximum to minimum resistance that can be obtained from these wires?
Why heat is generated across a resistor when the electric field is applied?
Why do electric acquire a steady drift velocity?
Why ammeter is always connected in series?
A wire is stretched to double its length. What happens to its resistance?
The energy that can be extracted from a storage battery is always less than the energy that goes into it while charging. Why?
The resistance of an ammeter must essentially be very small. Why?
Water boils in an electric kettle in 15 after being switched on. Using the same main supply. Should the length of the heating element be increased or decreased if the water is to boil in 10 minutes? Explain.
What is the ratio of maximum to minimum resistance obtained from n wires of resistance R each?
Why is it essential that the resistance of a voltmeter be very high?
An ammeter is always connected in series. Why?
Distinguish between resistance and resistivity of a material.
Long-distance, electric power, transmission lines always operate at very high voltage, some time as much as 750 kV. What are the advantages of such high voltage?
Distinguish between resistance and resistivity. Derive expressions for the effective resistance of number of resistors connected in series and parallel.

Long Questions

Deduce an expression for the heat developed in a wire by the passage of an electric current.
What do you mean by a shunt? Describe its use in converting a galvanometer into an ammeter.
What is drift velocity of an electron? Derive a relation between the current through a metallic conductor and the drift velocity in terms of the number of free electrons per unit volume of the conductor.
Discuss the mechanism of metallic conduction. Derive j=new where j is the current density, e is the electronic charge and v is drift velocity.
State and explain joule`s laws of electric current. Discuss how they are verified experimentally.
What do you meant by shunt? How will you convert a galvanometer into an ammeter?
State and explain Ohm`s law. Two resistors are connected in parallel and third resistor be connected in series with the combination of parallel resistors. If this combination be connected with a battery of the negligible internal resistance, find the potential difference across each resistor.
What is meant by a shunt? How will you convert a galvanometer into a ammeter?
Discuss the mechanism of metallic conduction. Derive a relation between current density and drift velocity.

Acoustic Phenomena

Physics XII Notes — Sat, 12 Jul 2014 05:41:42 +0000

Short Answer Questions

How are beats produced? What is beat frequency?
What are ultrasonic and infrasonic?
Distinguish between ultrasonic and supersonic’s.
How it is that one can recognize a friend from his voice without seeing him?
Why is it roaring of a lion different than the sound of a mosquito?
What do you mean by the term threshold of hearing?
Whistle of an approaching train is shriller. Why?
Define beats and beat frequency.
Bells are made of metal and not of wood, why?
Explain with a figure the meaning of beats.
Two notes, one produced by violin and the other by a sitar, may have the frequency, yet we can distinguish between them. Why?
Which has a more direct influence on the sound wave: the observer is approaching the stationary sound source.
What is meant by threshold of hearing?

Long

Deduce the expressions for the frequency herd by an observer, when the observer is approaching the stationary sound source.
What is Doppler`s effect? Derive an expression for the apparent frequency received by a stationary observer when a source is moving away from him.
What do you mean by intensity and intensity level of sound? Define bel and decibel.
What are beats? Prove that the number of beats per second is equal to the difference between the frequencies of two superposing waves.
What is Doppler`s effect? Derive the change in frequency when an observer moves towards a stationary source?
Discuss the phenomenon of Doppler`s effect. Find the change in frequency when a moving source of sound passes a stationery observer.
Define intensity of sound. Show that the intensity of sound for a given frequency is directly proportional to the square of amplitude of vibration.

8 Define the intensity of sound and prove that l=1/2pVr2w2 where the symbols have their usual meaning.

What is the Doppler Effect in sound? Obtain an expression for the apparent frequency of the sound when the source and observer both move in the same direction.
Define intensity and deduce it in terms of amplitude of vibration, density of medium, angular velocity and velocity of the wave.
What are beats? Obtain an expression for the beat frequency when beats are produced by superposing two waves of slightly different frequencies.
What is Doppler`s Effect? Deduce an expression for the apparent frequency heard by a stationary observer when a source approaches towards him.

Alternating Currents

Physics XII Notes — Sat, 12 Jul 2014 05:41:42 +0000

Short Questions

Why do we prefer a choke coil to rheostat in an a.c. current?
What is meant buy independence of an a.c. current?
Why is choke coil preferable to resistor?
Why is choke considered superior to a rheostat?
What do you mean by r.m.s value of an AC current?
What is meant by wattles current?
Fluorescent tubes often use an inductor to limit the current through the tube. Why is it better to use inductor than a resistor for this purpose?
Why is a choke coil better than a resistor ina n electrical appliences?
Define rms value of alternating current.
What are the advantages of a.c. over d.c.?
A chock coil is preferred to a resistor in an ac current. Why?

Long Questions

Discuss the phase relationship between the voltage and current in the ac current containing inductance and resistance. What is power factor of the circuit?
Find the impendence of LCR circuit in series.
An alternating emf is applied across a capacitor. Show that the current in its leads to the applied emf by 90°.
An a.c. passes through a circuit containing a resistor and a inductor in series. Derive an expression for the phase relation between the current and the voltage.
Discuss the phase relationship between the voltage and current in the a.c. circuit containing capacitor and resistor in series and hence derive an expression for the impedance of the circuit.
Derive the condition for resonant frequency of an LCR alternating current series circuit.
Derive an expression of current flowing through a.c. circuit containing a resistor and capacitor in series combination. What is the power factor of this circuit?
Discuss the phase relationship between the circuit and voltage in a.c. circuit containing capacitor and resistor in series and hence derive an expression for the impedance of the circuit.