Electric Charges and Fields — Physics STD 12 Science — Question

If a slab of insulating material 4   thick is introduced between the plates of a parallel plate capacitor, the separation between plates has to be increased by 3.5   to restore the capacity to original value. The dielectric constant of the material will be

(a) 6

(b) 8

(c) 10

(d) 12

Two uncharged bodies on rubbing, get charged due to:

Two resistances R and 2R are connected in parallel in an electric circuit. The thermal energy developed in R and 2R are in the ratio:

1. 1 : 2
2. 2 : 1
3. 1 : 4
4. 4 : 1

A circular loop carrying a current is replaced by an equivalent magnetic dipole. A point on the axis of the loop is

(a) An end-on position	(b) A broad side-on position
(c) Both (a) and (b)	(d) Neither (a) nor (b)

A man wishing to get a picture of a Zebra photographed a white donkey after fitting a glass with black streaks onto the objective of his camera.

A rectangular loop carrying a current i is situated near a long straight wire such that the wire is parallel to the one of the sides of the loop and is in the plane of the loop. If a steady current I is established in wire as shown in figure, the loop will

(a) Rotate about an axis parallel to the wire

(b) Move away from the wire or towards right

(c) Move towards the wire

(d) Remain stationary

Forty electric bulbs are connected in series across a 220 V supply. After one bulb is fused, the remaining 39 are connected again in series across the same supply. The illumination will be

(a) More with 40 bulbs than with 39	(b) More with 39 bulbs than with 40
(c) Equal in both the cases	(d) In the ratio of

Which color band in the resistor is having highest tolerance?

Three capacitors of 2μF, 3μF  and 6μF  are joined in series and the combination is charged by means of a 24 volt battery. The potential difference between the plates of the 6 μF  capacitor is

(a) 4 volt

(b) 6 volt

(c) 8 volt

(d) 10 volt