StemCET Logo

Physics Question 49 – JEE-MAIN 2026

← Back
A three coulomb charge moves from the point (0,−2,−5) to the point (5,1,2) in an electric field expressed as E→=2xi^+3y2j^+4k^ N/C. The work done in moving the charge is _______ J.

The work done by an electric field on a charge is given by the line integral of the electric force over the path.

● Video Walkthrough
Step 1: Identify the formula for work done✦ Active

The work done W by an electric field E→ on a charge q moving from an initial point A to a final point B is given by the line integral:

W=q∫ABE→⋅dl→

Given charge q=3 C. The electric field is E→=2xi^+3y2j^+4k^ N/C. The differential displacement vector is dl→=dxi^+dyj^+dzk^. The initial point is A=(0,−2,−5) and the final point is B=(5,1,2).

Step 2: Calculate the dot product and set up the integral○ Expand

First, calculate the dot product E→⋅dl→:

E→⋅dl→=(2xi^+3y2j^+4k^)⋅(dxi^+dyj^+dzk^)=2xdx+3y2dy+4dz

Now, set up the integral for the work done:

W=q∫AB(2xdx+3y2dy+4dz) W=q(∫xAxB2xdx+∫yAyB3y2dy+∫zAzB4dz) W=3(∫052xdx+∫−213y2dy+∫−524dz)
Step 3: Evaluate the integrals and find the total work done○ Expand

Evaluate each definite integral:

∫052xdx=[x2]05=52−02=25 ∫−213y2dy=[y3]−21=13−(−2)3=1−(−8)=9 ∫−524dz=[4z]−52=4(2)−4(−5)=8−(−20)=28

Sum the results and multiply by the charge q=3 C to find the total work done:

W=3(25+9+28)=3(62)=186 J
✦ STEM Console utilizes AI models to generate step-by-step explanations and math clues. AI can make mistakes.