Current Electricity — Physics STD 12 Science — Question

A given charge is situated at a certain distance from an electric dipole in the end-on position experiences a force F. If the distance of the charge is doubled, the force acting on the charge will be

(a) 2F

(b) F / 2

(c) F / 4

(d) F / 8

Which of the following quantities do not depend on the choice of zero potential or zero potential energy?

Electromagnetic waves are produced by:

A tuning fork of frequency 512Hz is vibrated with a sonometer wire and 6 beats per second are heard. The beat frequency reduces if the tension in the string is slightly increased. The original frequency of vibration of the string is:

1. 506Hz
2. 512Hz
3. 518Hz
4. 524Hz.

In a radioactive decay, neither the atomic number nor the mass number changes. Which of the following would be emitted in the decay process

(a) Proton

(b) Neutron

(c) Electron

(d) Photon

A 10 V storage battery of negligible internal resistance is connected across a 50 Ω resistor. How much heat energy is produced in the resistor in 1 hour

(a) 7200 J

(b) 6200 J

(c) 5200 J

(d) 4200 J

The mass number of a nucleus is

(a) Always less than its atomic number

(b) Always more than its atomic number

(c) Always equal to its atomic number

(d) Sometimes more than and sometimes equal to its atomic number

A convex lens of focal length 12 cm is made of glass of μ = . What will be its focal length when immersed in liquid of μ =  

(a) 6 cm

(b) 12 cm

(c) 24 cm

(d) 30 cm

An electron of mass m and charge q is travelling with a speed v along a circular path of radius r at right angles to a uniform of magnetic field B. If speed of the electron is doubled and the magnetic field is halved, then resulting path would have a radius of

(a)

(b)

(c) 2r

(d) 4r

If an electric dipole is placed in an electric field, then the value of the torque acting on it will be: