Semiconductor Electronic: Material, Devices And Simple Circuits — Physics STD 12 Science — Question

A virtual image three times the size of the object is obtained with a concave mirror of radius of curvature 36 cm. The distance of the object from the mirror is

(a) 5 cm

(b) 12 cm

(c) 10 cm

(d) 20 cm

Let E₁​ and E_2​ be the binding energies of two nuclei A and B. It is observed that two nuclei of A combine together to form a B nucleus. This observation is correct only if:

A proton is moving along Z-axis in a magnetic field. The magnetic field is along X-axis. The proton will experience a force along

(a) X-axis

(b) Y-axis

(c) Z-axis

(d) Negative Z-axis

A cell of negligible resistance and e.m.f. 2 volts is connected to series combination of 2, 3 and 5 ohm. The potential difference in volts between the terminals of 3 ohm resistance will be

(a) 0.6

(b) 2/3

(c) 3

(d) 6

Ohm's law is true

(a) For metallic conductors at low temperature

(b) For metallic conductors at high temperature

(c) For electrolytes when current passes through them

(d) For diode when current flows

Three capacitors of capacitances 3 μF, 9μF  and 18 μF  are connected once in series and another time in parallel. The ratio of equivalent capacitance in the two cases will be

(a) 1 : 15

(b) 15 : 1

(c) 1 : 1

(d) 1 : 3

The SI unit of electrical energy is ____________?

Assertion   :   Electric appliances with metallic body; e.g. heaters, presses etc, have three pin connections, whereas an electric bulb has a two pin connection.

Reason    : Three pin connections reduce heating of connecting cables.

(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.

(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.

(c) If assertion is true but reason is false.

(d) If the assertion and reason both are false.

At the magnetic North Pole of the Earth, what is the value of the angle of dip?

The stopping potential V for photoelectric emission from a metal surface is plotted along Y-axis and frequency n of incident light along X-axis. A straight line is obtained as shown. Planck's constant is given by

(a) Slope of the line

(b) Product of slope on the line and charge on the electron

(c) Product of intercept along Y-axis and mass of the electron

(d) Product of Slope and mass of electron