Atoms — Physics STD 12 Science — Question

Assertion   :   Inductance coil are made of copper.

Reason       : Induced current is more in wire having less resistance.

(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.

Magnetic effect of current was discovered by

(a) Faraday

(b) Oersted

(c) Ampere

(d) Bohr

Shown in the figure here is a convergent lens placed inside a cell filled with a liquid. The lens has focal length + 20 cm when in air and its material has refractive index 1.50. If the liquid has refractive index 1.60, the focal length of the system is

(a) + 80 cm

(b) – 80 cm

(c) – 24 cm

(d) –100 cm

The unit of focal power of a lens is

(a) Watt

(b) Horse power

(c) Dioptre

(d) Lux

In an elastic collision:

1. The kinetic energy remains constant.
2. The linear momentum remains constant.
3. The final kinetic energy is equal to the initial kinetic energy.
4. The final linear momentum is equal to the initial linear momentum.

Magnitude of current at half power point in a circuit is:

In the diagram shown, the reading of voltmeter is 20 V and that of ammeter is 4 A. The value of R should be (Consider given ammeter and voltmeter are not ideal)

(a) Equal to 5Ω

(b) Greater from 5 Ω

(c) Less than 5 Ω

(d) Greater or less than 5 Ω  depends on the material of R

Which one of the following graphs in following figure represents variation of reactance ′X_c′​ of a capacitor with frequency 'f' of an ac supply?

A condenser having a capacity 2.0 micro farad is charged to 200 volts and then the plates of the capacitor are connected to a resistance wire. The heat produced in joules will be

(a) 4

(b) 4

(c) 4

(d) 2