Electrostatic Potential and Capacitance — Physics STD 12 Science — Question

A current of two amperes is flowing through a cell of e.m.f. 5 volts and internal resistance 0.5 ohm from negative to positive electrode. If the potential of negative electrode is 10V, the potential of positive electrode will be

(a) 5 V

(b) 14 V

(c) 15 V

(d) 16 V

Figure shows the electric lines of force emerging from a charged body. If the electric field at A and B are   and   respectively and if the displacement between A and B is r then

(a)

(b)

(c)

(d)

The three basic properties possessed by the electric charge are:

An electron revolves around the nucleus of hydrogen atom in a circle of radius 5 × 10^-11 m. The intensity of electric field at a point in the orbit of the electron is:

Match the List I with the List II from the combinations shown

(I)	Presbiopia	(A)	Sphero-cylindrical lens
(II)	Hypermetropia	(B)	Convex lens of proper power may be used close to the eye
(III)	Astigmatism	(C)	Concave lens of suitable focal length
(IV)	Myopia	(D)	Bifocal lens of suitable focal length

(a) I-A; II-C; III-B; IV-D

(b) I-B; II-D; III-C; IV-A

(c) I-D; II-B; III-A; IV-C

(d) I-D; II-A; III-C; IV-B

The dominant mechanisms for motion of charge carriers in forward and reverse biased silicon P-N junctions are

(a) Drift in forward bias, diffusion in reverse bias

(b) Diffusion in forward bias, drift in reverse bias

(c) Diffusion in both forward and reverse bias

(d) Drift in both forward and reverse bias

Assertion  :   X-rays can penetrate through the flesh but not through the bones.

Reason      : The penetrating power of X-rays depends on voltage.

(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.

In an experiment of meter bridge, a null point is obtained at the centre of the bridge wire. When a resistance of 10 ohm is connected in one gap, the value of resistance in other gap is

(a) 10 Ω

(b) 5 Ω

(c)

(d) 500 Ω

Current flowing through the ideal diode shown in the circuit is __________ .

A horizontal rod of mass 10 gm and length 10 cm is placed on a smooth plane inclined at an angle of 60° with the horizontal, with the length of the rod parallel to the edge of the inclined plane. A uniform magnetic field of induction B is applied vertically downwards. If the current through the rod is 1.73 ampere, then the value of B for which the rod remains stationary on the inclined plane is

(a) 1.73 Tesla

(b)  Tesla

(c) 1 Tesla

(d) None of the above