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

Consider the following two statements:

1. The linear momentum of a particle is independent of the frame of reference.
2. The kinetic energy of a particle is independent of the frame of reference.

1. Both A and B are true.
2. A is true but B is false.
3. A is false but B is true.
4. Both A and B are false.

A 10 micro-farad capacitor is charged to 500 V and then its plates are joined together through a resistance of 10 ohm. The heat produced in the resistance is

(a) 500 J

(b) 250 J

(c) 125 J

(d) 1.25 J

Which of the following transitions in a hydrogen atom emits photon of the highest frequency

(a) n = 1 to n = 2

(b) n = 2 to n = 1

(c) n = 2 to n = 6

(d) n = 6 to n = 2

Identify the definition of sensitivity of a galvanometer from the following.

When a point source of light is at a distance of one metre from a photo cell, the cut off voltage is found to be V. If the same source is placed at 2 m distance from photo cell, the cut off voltage will be

(a) V

(b) V/2

(c) V/4

(d) V/

A parallel plate capacitor of capacitance C is connected to a battery and is charged to a potential difference V. Another capacitor of capacitance 2C is connected to another battery and is charged to potential difference 2V. The charging batteries are now disconnected and the capacitors are connected in parallel to each other in such a way that the positive terminal of one is connected to the negative terminal of the other. The final energy of the configuration is

(a) Zero

(b)

(c)

(d)

Pick out the electromagnetic wave which is highly harmful to humans.

The magnetic flux linked with a loop of wire placed in a magnetic field does not depend upon :

For driving a current of 2 A for 6 minutes in a circuit, 1000 J of work is to be done.  The e.m.f. of the source in the circuit is

(a) 1.38 V

(b) 1.68 V

(c) 2.04 V

(d) 3.10 V

Figure shows a conducting loop being pulled out of a magnetic field with a speed u. Which of the four plots shown in figure may represent the power delivered by the pulling agent as a function of the speed u?