Science (English Medium) Class 12 - CBSE Question Bank Solutions for Physics

Which of the following statements about a series LCR circuit connected to an ac source is correct?

An alternating voltage of 220 V is applied across a device X. A current of 0.22 A flows in the circuit and it lags behind the applied voltage in phase by π/2 radian. When the same voltage is applied across another device Y, the current in the circuit remains the same and it is in phase with the applied voltage.

1. Name the devices X and Y and,
2. Calculate the current flowing in the circuit when the same voltage is applied across the series combination of X and Y.

An increase in the intensity of the radiation causing photo-electric emission from a surface does not affect the maximum K.E. of the photoelectrons. Explain.

Draw the phasor diagram for a series LRC circuit connected to an AC source.

When an alternating voltage of 220V is applied across device X, a current of 0.25A flows which lags behind the applied voltage in phase by π/2 radian. If the same voltage is applied across another device Y, the same current flows but now it is in phase with the applied voltage.

1. Name the devices X and Y.
2. Calculate the current flowing in the circuit when the same voltage is applied across the series combination of X and Y.

A series LCR circuit is connected to an ac source. Using the phasor diagram, derive the expression for the impedance of the circuit.

(i) In Young's double-slit experiment, deduce the condition for (a) constructive and (b) destructive interferences at a point on the screen. Draw a graph showing variation of intensity in the interference pattern against position 'x' on the screen.

(b) Compare the interference pattern observed in Young's double-slit experiment with single-slit diffraction pattern, pointing out three distinguishing features.

Define ionization energy.

Calculate the shortest wavelength of the spectral lines emitted in Balmer series.

[Given Rydberg constant, R = 10⁷ m^–1]

Use Biot-Savart law to derive the expression for the magnetic field on the axis of a current carrying circular loop of radius R.

Draw the magnetic field lines due to a circular wire carrying current I.

(i) Explain with the help of a diagram the formation of depletion region and barrier potential in a pn junction.

Explain the meaning of the term mutual inductance.

Why is base band signal not transmitted directly? Give any two reasons

Derive an expression for path difference in Young’s double slit experiment and obtain the conditions for constructive and destructive interference at a point on the screen.

The intensity at the central maxima in Young’s double slit experiment is I₀. Find out the intensity at a point where the path difference is` lambda/6,lambda/4 and lambda/3.`

What happens when a forward bias is applied to a p-n junction?

What causes the setting up of high electric field even for small reverse bias voltage across the diode?

In young’s double slit experiment, deduce the conditions for obtaining constructive and destructive interference fringes. Hence, deduce the expression for the fringe width.

Show that the fringe pattern on the screen is actually a superposition of slit diffraction from each slit.

How does one explain, using de Broglie hypothesis, Bohr's second postulate of quantization of orbital angular momentum?