Atoms — Physics STD 12 Science — Question

In the adjoining circuit, the battery  has an e.m.f of 12 volt and zero internal resistance while the battery E has an e.m.f  of 2 volt. If the galvanometer G reads zero, then the value of the resistance X in ohm is

(a) 10

(b) 100

(c) 500

(d) 200

If the angles of dip at two places are 30^o and 45^o respectively, then the ratio of horizontal  components of earth's magnetic field at the two places will be

(a)

(b) 1 :

(c) 1 :

(d)  1 : 2

What is the order of potential difference built up by the Van de Graff generator?

If a battery of 12 V is connected across the diametrically end points A & B of a conducting ring of radius R and the current drawn from the battery is I , then the magnetic field produced at the centre of the ring due to the ring is ___________ .

The electric potential at a point (x, y) in the  x - y  plane is given by V = -kxy. The field intensity at a distance r from the origin varies as

(a)

(b) r

(c)

(d)

A circular loop of radius 0.0157m carries a current of 2.0 amp. The magnetic field at the centre of the loop is (

(a) 1.57	(b) 8.0
(c) 2.5	(d)  3.14

If 200 MeV energy is released in the fission of a single  nucleus, the number of fissions required per second to produce 1 kilowatt power shall be (Given 1eV = 1.6

(a) 3.125

(b) 3.125

(c) 3.125

(d) 3.125

Two wires of same length are shaped into a square and a circle. If they carry same current, ratio of the magnetic moment is

(a) 2 : π

(b) π : 2

(c) π : 4

(d) 4 : π

In the arrangement shown in given Figure, there are two coils wound on a non-conducting cylindrical rod. Initially the key is not inserted. Then the key is inserted and later removed. Then,

In order to stop a car in shortest distance on a horizontal road, one should:

1. Apply the brakes very hard so that the wheels stop rotating.
2. Apply the brakes hard enough to just prevent slipping.
3. Pump the brakes (press and release).
4. Shut the engine off and not apply brakes.