Electric Charges and Fields — Physics STD 12 Science — Question

Eight small drops, each of radius r and having same charge q are combined to form a big drop. The ratio between the potentials of the bigger drop and the smaller drop is

(a) 8 : 1

(b) 4 : 1

(c) 2 : 1

(d) 1 : 8

The binding energy per nucleon is maximum in the case of

(a)

(b)

(c)

(d)

An elastic circular wire of length l carries a current I. It is placed in a uniform magnetic field   (Out of paper) such that its plane is perpendicular to the direction of . The wire will experience

(a) No force	(b) A stretching force
(c) A compressive force	(d) A torque

The magnetic moment of a magnet of length 10 cm and pole strength 4.0 Am will be

(a)

(b) 1.6

(c) 20

(d) 8.0

A plane wave front falls on a convex lens. The emergent wave front is:

In Young's double slit experiment, the distance between sources is 1 mm and distance between the screen and source is 1 m. If the fringe width on the screen is 0.06 cm, then λ =    

(a) 6000 Å

(b) 4000 Å

(c) 1200 Å

(d) 2400 Å

The coefficient of mutual induction between two coils is 4H. If the current in the primary reduces from 5A to zero in 10^-3 second then the induced emf in the secondary coil will be

Assertion  :   In Millikan's experiment for the determination of charge on an electron, oil drops of any size can be used.

Reason      : Millikan's experiment determine the charge on electron, by simply measuring the terminal velocity.

(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 assertion is false but reason is true.

A capacitor of capacitance 5  is connected as shown in the figure. The internal resistance of the cell is 0.5 Ω. The amount of charge on the capacitor plate is

(a) 0

(b) 5

(c) 10

(d) 25

Which of the following is a natural magnet?