Current Electricity — Physics STD 12 Science — Question

Let F_pp, F_pn and F_nn denote the magnitudes of the net force by a proton on a proton, by a proton on a neutron and by a neutron on a neutron respectively. Neglect gravitational force. When the separation is 1fm:

1. F_pp > F_pn = F_nn
   
2. F_pp = F_pn = F_nn
   
3. F_pp > F_pn > F_nn
   
4. F_pp < F_pn = F_nn
   

A hollow metal sphere of radius 5cm is charged such that the potential on its surface is 10V. The potential at a distance of 2cm from the centre of the sphere

(a) Zero

(b) 10 V

(c) 4 V

(d) 10/3 V

The momentum of photon is :

If the direction of the initial velocity of the charged particle is neither along nor perpendicular to that of the magnetic field, then the orbit will be

(a) A straight line

(b) An ellipse

(c) A circle

(d) A helix

The tangent at any point of  field line gives the direction of:

Assertion : Ultraviolet radiation are of higher frequency waves are dangerous to human being.

Reason    : Ultraviolet radiation are absorbed by the atmosphere

(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.

Number of electrons in 1 Coulomb charge is _________?

Two identical cells send the same current in 2Ω resistance, whether connected in series or in parallel. The internal resistance of the cell should be

(a) 1 Ω

(b) 2 Ω

(c)

(d) 2.5 Ω

Magnetic moments of two bar magnets may be compared with the help of

(a)  Deflection magnetometer	(b) Vibration magnetometer
(c) Both of the above	(d) None of the above

A region surrounding a stationary electric dipoles has: