Question

When a charged particle moves in an electric field, work is done on the particle. 

1. Pick out a vector quantity from the following

• electric potential
• electric potential gradient
• electric potential energy
• electric flux 

2. 5 J  of work is done in moving a positive charge of 0.5 C between two points. What is the potential difference between the points?

• 2.5 V 
• 10 V 
• 0.1 V 
• 5.5 V 

3. Three-point electric charges q₁ = 6µC, q₂ = 4µC and q₃ = -8µC are placed on the circumference of a circle of radius 1 m as shown in the figure. What is the value of the charge q₄ placed on the circle if the potential at the centre of the circle is zero? 

Answer 1

1. Electric potential gradient

2. 10 V

3. Radius of the circle r = 1 m

By the given condition

\(\frac{1}{4\pi\varepsilon_0}\) x \(\frac{1}{r}\) (q₁ + q₂ + q₃ + q₄) = 0

(q₁ + q₂ + q₃ + q₄) = 0

(6 + 4 – 8 + q₄) µC = 0

(2 + q₄) µC = 0

q₄ = -2µC.