Free Printable Electrostatic Force

1.

Two charges +q and +2q are placed at the ends of a straight line. Another charge +q is placed at the midpoint of the line. Then the charge +q placed at the midpoint will:

a)

lie at rest

b)

move towards the bigger charge

c)

move towards smaller charge and then come to rest

d)

move towards the bigger charge and then come to rest.

2.

A charge q is placed at the centre of the line joining the two equal charges Q. This system of three charges will be in equilibrium if q is equal to:

a)

- Q/2

b)

– Q/4

c)

Q/4

d)

Q/2

3.

A charge q1 exerts some force on a second charge q2. A third charge q3 is brought near. Then, force exerted by q1 and q2 will:

a)

decrease in magnitude

b)

increase in magnitude

c)

remain unchanged

d)

increase, if q2 is of the same sign as q1 and will decrease, if q2 is o opposite sign.

4.

Five balls numbered 1 to 5 are suspended using separate threads. Pairs (1, 2), (2, 4) and (4, 1) show electrostatic attraction, while pairs (2, 3) and (4, 5) show repulsion. Therefore, ball 1 must be:

a)

positively charged

b)

negatively charged

c)

neutral

d)

made of metal.

5.

Three charges +4q, Q and q are placed in straight line of length l at points distance O, l/2 and l, respectively. What should be Q in order to make the net force on q to be zero.

a)

-q

b)

-2q

c)

– q/2

d)

4q.

6.

Four charges are arranged at the corners of a square ABCD [as shown in the figure]. The force on the charge +q kept at the centre of O is:

a)

along the diagonal AC

b)

along the diagonal BD

c)

perpendicular to the side AB

d)

zero.

7.

A small metal ball is suspended in a uniform electric field with the help of an insulated thread. If high energy X-ray beam falls on:

a)

the ball will be deflected in the direction of field

b)

the ball will be deflected opposite to the direction of field

c)

the ball will not deflect at all

d)

the ball will fly to infinity.

8.

Three charges each of +q are placed at the three vertices of an equilateral triangle. If the distance of centroid from each vertex of the triangle is r, then strength of electric field at the centroid will be:

a)

$\frac{3q}{4\Pi\xi o\ r},\$

b)

$\frac{3q}{4\Pi\xi o\ r^2},$

c)

$\frac{q}{4\Pi\xi o\ r^2},$

d)

zero

9.

Three charges each of +q are placed at the three vertices of an equilateral triangle. If the distance of centroid from each vertex of the triangle is r, then strength of electric field at the centroid will be:

a)

$\frac{3q}{4\Pi\xi o\ r},\$

b)

$\frac{3q}{4\Pi\xi o\ r^2},$

c)

$\frac{q}{4\Pi\xi o\ r^2},$

d)

zero

10.

Point charges +4q, -q and +4q are kept on the X-axis at points x = 0, and x = 2a, respectively:

a)

only -q is in stable equilibrium

b)

none of the charges are in unstable equilibrium

c)

all the charges are in unstable equilibrium

d)

all he charges are in the stable equilibrium.

11.

Two neutrons are separated by a distance r meter and have a coulomb force equal to F. Two alpha particles separated by 2r meter will have a force equal to:

a)

2F

b)

3F

c)

F/2

d)

F

12.

An electron of mass M, initially at rest, moves through a certain distance in a uniform electric field in time t1, A proton of mass Mp also initially at rest takes time t2 to move through an equal distance in this uniform electric field. Neglecting the effect of gravity, the ratio t2/t1, is nearly equal to:

a)

1

b)

$\sqrt[]{\frac{Mp}{Me}}$

c)

$\sqrt[]{\frac{Me}{Mp}}$

d)

1836

Electrostatic Force

Total questions: 12

Worksheet time: 6mins

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