Unit Test- class 12 (physics)

Which one of the following represents correct units for electric field strength?

• T

• N/C

• J/C

• a. N • m ² • C^-2

The flow of charge per unit time defines

• power

• current

• voltage

• resistance

The diagram shows two positive charges of magnitude Q and 2Q.

Which vector best represents the direction of the electric field at point P, which is equidistant from both charges?

• 
• 
• 
• 

A 6.0 x 10 ^–6 C charge is located 4.0 m from a –3.0 x 10 ^–6 C charge as shown in fig.

What is the electric potential at P, halfway between the charges?

• -4.1 x 10 ^–2 V

• 6.8 x 10 ³ V

• 1.35 x 10 ⁴ V

• 4.1 x 10 ⁴ V

The diagram shows the electric field near two point charges L and R.

• charge L - Positive and charge R - Positive

• charge L - Positive and charge R - Negative

• charge L - Negative and charge R - Positive

• charge L - Negative and charge R - Negative

The electric field 2.0 m from a point charge has a magnitude of 8. 0 x 10 ⁴ N/C. What is the strength of the electric field at a distance of 4.0 m?

• 2.0 x 10⁴ N/C

• 4.0 x 10⁴ N/C

• 1.6 x 10 ⁵ N/C

• 3.2 x 10 ⁵ N/C

When a charge is accelerated through a potential difference of 500 V, its kinetic energy increases from 2.0 x 10 ^-5 J to 6. 0 x 10 ^-5 J. What is the magnitude of the charge?

• 4.0 x 10 ^-8 C

• 8.0 x 10 ^-8 C

• 1. 2 x 10 ^-7 C

• 1. 6 x 10 ^-7 C

A negative charge in an electric field experiences a force accelerating it due south. What is the direction of the electric field?

• East

• West

• North

• South

A (- 2.3 x 10 ^-6) C charge exerts a repulsive force of magnitude 0.35 N on an unknown charge 0.20 m away. What are the magnitude and polarity of the unknown charge?

• MAGNITUDE- 6.8 x 10 ^–7 C and Polarity - Negative

• MAGNITUDE- 6.8 x 10 ^–7 C and Polarity - Positive

• MAGNITUDE- 1.2 x 10 ^–6 C and Polarity - Negative

• MAGNITUDE- 1.2 x 10 ^–6 C and Polarity - Positive

Two point charges, 2.5 x 10 ^-6 C and -5.0 x 10 ^-6 C , are placed 3.0 m apart as shown in fig.

What is the magnitude of the electric field at point P, midway between the two charges?

• 1.0 x 10⁴ N /C

• 2.0 x 10⁴ N/C

• 0 N/C

• 3.0 x 10⁴ N/C