Electric Fields Between Point Charges

00:00 7 marks

Two point charges, \(Q_{1} = +4.0\,\mu C\) and \(Q_{2} = -6.0\,\mu C\), are placed 0.20 m apart in a vacuum. Point P is located midway between the two charges.

Part a

1 minutes 1 marks

Question

Define electric field strength. [1]

Hint Hint

Hint

Recall that electric field strength is the force per unit positive test charge.

Answer Answer
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Complete Answer

The electric field strength is defined as the force per unit positive test charge.

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Part b

3 minutes 3 marks

Question

Calculate the magnitude and state the direction of the electric field strength at point P due to \(Q_{1}\). [3]

Hint Hint

Hint

Use \(E = k\frac{|Q|}{r^2}\) with \(r = 0.10\,m\).

Answer Answer
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Complete Answer

Approximately \(3.6 \times 10^6\,N\,C^{-1}\) directed away from \(Q_{1}\) (towards \(Q_{2}\)).

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Part c

3 minutes 3 marks

Question

Calculate the magnitude and state the direction of the resultant electric field strength at point P. [3]

Hint Hint

Hint

Combine the fields from both charges, keeping track of their directions.

Answer Answer
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Explanation Explanation

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Complete Answer

Approximately \(8.99 \times 10^6\,N\,C^{-1}\) directed towards \(Q_{2}\).

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