1. Consider a neutral conducting sphere. A

positive point charge is placed outside

the sphere. The net charge on the sphere

is then,

1. Negative and distributed uniformly

over the surface of the sphere.

2. Negative and appears only at the point

on the sphere closest to the point charge

3. Negative and distributed nonuniformly

over the entire surface of the

sphere

4. Zero

2. STATEMENT – 1

The formula connecting u, v and f for a

spherical mirror is valid only for mirrors

whose sizes are very small compared to

their radii of curvature.

because

STATEMENT-2

Laws of reflection are strictly valid for

plane surfaces, but not for large

spherical surfaces.

a. Statement-I is true, Statement-2 is

True ; Statement-2 is a correct

explanation for Statement-I

b. Statement-1 is true, Statement-2 is

True ; Statement-2 is NOT a correct

explanation for Statement-I.

c. Statement-1 is True, Statement-2 is

False.

d. Statement-1 is False, Statement-2 is

True.

3.STATEMENT-1: If the accelerating

potential in an X-ray tube is increased,

the wavelengths of the characteristic Xrays

do not change. Because

STATEMENT-2 : When an electron

beam strikes the target in an X-ray tube,

part of the kinetic energy is converted

into X-ray energy.

a. Statement-1 is True, Statement-2 is

True; Statement-2 is a correct

explanation for Statement-1.

b. Statement-1 is True, Statement-2 is

True; Statement-2 is NOT a correct

explanation for Statement-1.

c. Statement-1 is True, Statement-2 is

False.

d. Statement-1 is False, Staement-2 is

True.

4. STATEMENT-1 : A block of mass m

starts moving on a rough horizontal

surface with a velocity v. It stops due to

friction between the block and the

surface after moving through a certain

distance. The surface is now tilted to an

angle of 30° with the horizontal and the

same block is made to go up on the

surface with the same initial velocity v.

The decrease in the mechanical energy

in the second situation is smaller than

that in the first situation. Because

STATEMENT-2 : The coefficient of

friction between the block and the

surface decreases with the increase in

the angle of inclination.

a. Statement-1 is True, Statement-2 is

True ; Statement-2 is a correct

explanation for statement-1.

b. Statement-1 is True, Statement-2 is

True; Statement-2 is NOT a correct

explanation for statement-1.

c. Statement-1 is True, Statement-2 is

False.

d. Statement-1 is False, Statement-2 is

True.

Source: 2007 JEE paper 1

## Sunday, October 11, 2009

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