Science (English Medium) इयत्ता १२ - CBSE Question Bank Solutions for Physics

Answer the following question.
What is the phase difference between the voltages across the inductor and the capacitor at resonance in the LCR circuit? 

Answer the following question.
Draw the diagram of a device that is used to decrease high ac voltage into a low ac voltage and state its working principle. Write four sources of energy loss in this device.  

Define the term: threshold frequency

Answer the following question.
Plot a graph of photocurrent versus anode potential for radiation of frequency ν and intensities I₁ and I₂ (I₁ < I₂).

Identify the part of the electromagnetic spectrum used in
(i) radar and
(ii) eye surgery. Write their frequency range.

On the basis of the graphs shown in the figure, answer the following questions :

(a) Which physical parameter is kept constant for the three curves?

(b) Which is the highest frequency among v₁, v_2, and v₃?

Write two distinguishing features of nuclear forces.

Name the radiation of the electromagnetic spectrum which is used for the following:

Radar and Give the frequency range.

Name the radiation of the electromagnetic spectrum which is used for the following:

To photograph internal parts of the human body and Give the frequency range

Name the radiation of the electromagnetic spectrum which is used for the following:

For taking photographs of the sky during the night and foggy conditions . Give the frequency range

Define the terms "stopping potential' and 'threshold frequency' in relation to the photoelectric effect. How does one determine these physical quantities using Einstein's equation?

Explain, with the help of a suitable example, how we can show that Lenz's law is a consequence of the principle of conservation of energy.

Use the expression for Lorentz force acting on the charge carriers of a conductor to obtain the expression for the induced emf across the conductor of length l moving with velocity v through a magnetic field B acting perpendicular to its length.

Using the phasor diagram, derive the expression for the current flowing in an ideal inductor connected to an a.c. source of voltage, v= v_o sin ωt. Hence plot graphs showing the variation of (i) applied voltage and (ii) the current as a function of ωt.

Derive an expression for the average power dissipated in a series LCR circuit.

The selectivity of a series LCR a.c. circuit is large, when ______.

Choose the correct answer from given options
The phase difference between the current and the voltage in series LCR circuit at resonance is

In the case of photoelectric effect experiment, explain the following facts, giving reasons.
The photoelectric current increases with increase of intensity of incident light.

Gamma rays and radio waves travel with the same velocity in free space. Distinguish between them in terms of their origin and the main application.

Define the term: stopping potential in the photoelectric effect.