Moving Charges and Magnetism — Physics STD 12 Science — Question

As the temperature of a conductor increases, its resistivity and conductivity change. The ratio of resistivity to conductivity:

Two bulbs are working in parallel order. Bulb A is brighter than bulb B. If  and   are their resistance respectively then

(a)

(b)

(c)

(d) None of these

A parallel-plate capacitor has plates of unequal area. The larger plate is connected to the positive terminal of the battery and the smaller plate to its negative terminal. Let Q₊ and Q_- be the charges appearing on the positive and negative plates respectively:

A convex lens of focal length 84 cm is in contact with a concave lens of focal length 12 cm. The power of combination (in diopters) is

(a) 25/24

(b) 25/18

(c) – 50/7

(d) + 50/7

The unit of magnetic flux is

(a)

(b) Weber

(c) Henry

(d) Ampere/m

The unit of electric field is not equivalent to

(a)  N/C

(b) J/C

(c) V/m

(d) J/C - m

Sixty-four drops are jointed together to form a bigger drop. If each small drop has a capacitance C, a potential V, and a charge q, then the capacitance of the bigger drop will be

(a) C

(b) 4C

(c) 16C

(d) 64C

Assertion  :  In Young’s experiment, the fringe width for dark fringes is different from that for white fringes.

Reason      : In Young’s double slit experiment the fringes are performed with a source of white light, then only black and bright fringes are observed.

(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.

The short range attractive nuclear forces that are responsible for the binding of nucleons in a nucleus are supposed to be caused by the role played by the particles called:

For making standard resistance, wire of following material is used: