# Electric Charges And Fields

15 Questions | Total Attempts: 9651  Settings  Time: 30 Minute

• 1.
The Gaussian surface for calculating the electric field due to a charge distribution is:
• A.

Any closed surface around the charge distribution

• B.

Any surface near the charge distribution

• C.

A spherical surface

• D.

A symmetrical closed surface at every point of which electric field has a single fixed value.

• 2.
Two copper spheres A and B of same size are charged to same potential. A is hollow and B is solid. Which of the two hold more charge?
• A.

Solid sphere cannot hold any change

• B.

Hollow sphere cannot hold any charge

• C.

Both have zero charge

• D.

Both have same charge

• 3.
The S.I. unit for surface integral of electric field is:
• A.

Vm

• B.

V

• C.
• D.
• 4.
The value of charge q at the centre of two equal and like charges Q so that the three are in equilibrium is:
• A.

Q

• B.

+Q/4

• C.

–Q/4

• D.

Q/2

• 5.
When an electric dipole is placed in a uniform electric field, it experiences
• A.

A force as well as torque

• B.

A torque but no force

• C.

A force but no torque

• D.

Neither a force nor a torque

• 6.
Two point charges at a certain distance experience a force of 5 newton. Each charge is doubled in magnitude and distance between the two is halved. The interacting force would be:
• A.

16 N

• B.

80 N

• C.

5 N

• D.

20 N

• 7.
If one penetrates a uniformly charged spherical shell, the electric field strength E:
• A.

Increases

• B.

Decreases

• C.

Remains the same as at the surface

• D.

Is zero at all points

• 8.
A positively charged ball hangs from a silk thread. We put positive test charge q0 at a point and measure F/q0 then it can be predicted that the electric field strength E is:
• A.

> F/q0

• B.

= F/q0

• C.

< F/q0

• D.

None of the above

• 9.
Electric field at the centroid of a triangle carrying q charge at each corner is:
• A.
• B.
• C.
• D.

Zero

• 10.
There is an electric field E in X-direction. If work done in moving a charge 0.2 c through a distance of 2m along a line making an angle of 60 degree with X-axis is 0.4 joule, what is the value of E?
• A.
• B.

4 N / C

• C.

5 N / C

• D.

None of these

• 11.
A charged spherical shell does not produce an electric field at any:
• A.

Interior point

• B.

Outer point

• C.

Beyond 2 meters

• D.

Beyond 10 meters

• 12.
The figure is plot of lines of force due to two charges q1 and q2.; Figure out the sign of charges.
• A.

Both negative

• B.

Both positive

• C.

Left positive and right negative

• D.

Right negative and left positive

• 13.
The unit permittivity of free space  is:
• A.

C/N-m

• B.
• C.
• D.
• 14.
If the electric flux entering and leaving an enclosed surface respectively is   and , the electric charge inside the surface will be:
• A.
• B.
• C.
• D.
• 15.
Two equal metal balls are charged to 10 and -20 units of electricity. Then they are brought in contact with each other and then again separated to original distance. The ratio of the magnitudes of forces between the balls before and after contact is:
• A.

8 : 1

• B.

1 : 8

• C.

1 : 2

• D.

2 : 1

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