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## SEMICONDUCTOR DEVICES–CLASS 12 PHYSICS QUESTION BANK

1. Draw a circuit diagram of OR gate.

2. What is a logic gate?

3. What types of charge-carriers are there in a n-type semi conductor?

4. Give the logical symbol of an AND gate. Mark the inputs and outputs.

5. Draw the logic symbol for a NAND gate.

6. Which biasing will make the resistance of p-n junction high?

7. Write the truth table for OR gate.

8. What is the change in the collector current, in a transistor of a.c. current gain 150, for a 100µA change in its base current?

9. When the voltage drop across a p-n junction diode is increased from 0.65V to 0.70V, the change in the diode current is 5mA. What is the dynamic resistance of the diode?

10. How does conductivity of a semiconductor change with rise in its temperature? (more…)

## Class 12 Physics : Electrostatics Revision Test

__Max marks:50 Time:2hrs__

- A glass rod rubbed with silk acquires a charge of 6×10
^{-12}C. Calculate the number of electrons it has gained or lost. (1) - If the magnitude of each charge becomes doubled, the separation between them is halved and the system of charges kept in a medium of=3 Calculate the force between them. (1)
- If two equal charges separated by a distance of 2m in air medium experiences a force of 0.9×10
^{10}C, Calculate the magnitude of each charge. (1) - Electric field intensity is 400Vm
^{-1}at a distance of 2 m from a point charge. At what distance it will become 100 Vm^{-1}? (1) - What will be the force experienced by a particle of charge 2µC placed in an electric field of 10kVm
^{-1}? (1) - What is the work done by moving 400μF charge between two points separated by a distance of 27 cm on an equipotential surface? (1)
- Calculate the number of electric lines of force from a charge 1.7708X10
^{-6}C in air medium? (1) - Two protons ‘A’ and ‘B’ are placed between two parallel plates having a potential difference ‘V’ as shown in the figure. Will these protons experience equal or unequal force? (1)
- Draw an equipotential surface for a point charge q> 0(1)
- The capacitance of a parallel plate capacitor is ‘C’. If 15 such capacitors are connected in series and then in parallel, what is the ratio of effective capacitance of first case to the second? (1)
- What is electric polarization ,polar and non polar molecules?( 2)
- 2) Define electrostatic induction and corona discharge. ( 2)
- Calculate the ratio of force experienced by a proton to that of the electron placed in an electric field of 4KVm
^{-1}. ( 2) - If an electrician has three capacitors of capacitances 4µF, 7µF& 12µF. How should he connect them, So that the effective capacitance will be 10µF? ( 2)
- Define the SI unit of potential difference and charge. ( 2)
- Two charges of 20µC and -20µC are placed 20 cm apart at points A and B respectively. Compute the electric field strength at point C, 20 cm away from both A and B.(3)
- Three capacitors of capacitances 4µF, 6µF and 8µF are connected parallel to each other and the combination is connected across a battery of 25V. Calculate the charges present on each capacitor and the total charge flows from the source. (3)
- Derive an expression for the torque experienced by a dipole in an external electric field. (3)
- Obtain an expression for the capacitance of a parallel plate capacitor. (3)
- Derive the relation E= (3)
- Derive an expression for the potential at a point due to dipole. Write the special cases also.(5)
- Derive an expression for ‘E’ at a point on the axial line of the dipole. (5)
- Explain with a neat diagram the principle, construction and working of a
**Van de Graff**generator. (5)

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## Class XI Physics Chapter wise Revision Test – Gravitation and Waves

**PHYSICS TESTPAPER**

**CLASS XI**

**GRAVITATION AND WAVES**

**Instructions**

*Questions 1 to 5 carries one mark each*

*Questions 5 to 10 carries 2 marks each*

*Questions 10 to 15 carries 3 marks each*

*Questions 16 and 17 carries 5 marks each*

* *

- What are mechanical waves?
- The time period of a vibrating source producing sound is 0.01 s. If the velocity of sound is 340 ms -1 calculate wave length
- State the principle of superposition of waves
- Why is gravitational potential energy negative?
- What is geosynchronous satellite?
- Derive a relation between wave velocity, frequency and wavelength
- What are transverse and longitudinal wave motions? Give an example for each type
- What is the effect of pressure on the speed of sound? Justify your answer.
- What is a progressive wave? Write an expression which represents a progressive wave.
- State the conditions necessary for a satellite to appear stationary.
- Define orbital velocity. Derive an expression for it.
- Define acceleration due to gravity. Show that the value of ‘g’ decreases with altitude or height
- State the laws of vibrations of stretched strings.
- Derive an expression for the escape velocity of a satellite projected from the surface of the earth.
- What is the maximum value of potential energy that can be possessed by a heavenly body? Give the general expression for potential energy of an object near the surface of earth
- State Kepler’s law of planetary motion. Deduce Newton’s law of gravitation from Kepler’s law.
- (a)What is Doppler Effect? (b) Derive an expression for the apparent frequency when a source moves towards a stationary observer. (c) A policeman on duty detects a drop of 15% in the pitch of the horn of a motor car as it crosses him. Calculate the speed of car, if the velocity of sound is 330 m/s

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## Class XI Physics Revision Tests – Thermodynamics

**PHYSICS TEST PAPER**

**THERMODYNAMICS**

Max marks 35

Time 1 ½ hrs

*Questions 1 to 5: 1 mark each*

*Questions 6 to 10: 2 marks each*

*Questions 11 to 15: 3 marks each*

*Question 16: 5 marks*

- What is an isochoric process?
- On what factors does the efficiency of a Carnot engine depend?
- State second law of thermodynamics. (Any one statement)
- State zeroth law of thermodynamics.
- What is a heat engine?
- State first law of thermodynamics and apply it to an isothermal process.
- Explain why a balloon is cooler after it bursts.
- What is a PV diagram? What does the area between the PV curve and the volume axis signify?
- State the conditions for two bodies to be in thermal equilibrium.
- State Carnot’s theorem and explain its significance.
- What is a cyclic process? Show that the work done in a cyclic process is equal to the area enclosed by the loop representing the cyclic process.
- Why gases have two principal specific heat capacities? Define them
- Why C
_{p}> C_{v}? Prove that C_{p}– C_{v}= R - Define the coefficient of performance of a heat pump. (refrigerator) and obtain a relation for it in terms of temperature T
_{1}and T_{2} - A sample of gas (γ = 1.5) is compressed adiabatically from a volume of 1600 cm
^{3}to 400 cm^{3}. If the initial pressure is 150 kPa, what is the final pressure and how much work is done on the gas in the process? - Explain the construction and various operations involved in a Carnot’s heat engine with neat labeled diagram. Draw Carnot’s cycle and write expression for efficiency of a Carnot’s heat engine.

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