Figure shows the field lines of a positive charge. Is the work done...

Question

Figure shows the field lines of a positive charge. Is the work done by the field in moving a small positive charge from Q to P positive or negative? Give reason.

Accepted Answer

Answer: Work done is NEGATIVE

Setup (as per standard CBSE figure):
• Q is farther from the source positive charge
• P is closer to the source positive charge

Step 1: Compare potentials
Since potential due to a positive charge V = kq/r decreases with distance:
• V_P > V_Q (P is closer, so higher potential)

Step 2: Apply work-energy formula
Work done by field: W = q(V_initial - V_final)
W = q(V_Q - V_P)

Step 3: Determine sign
Since V_Q = V_P, we get (V_Q - V_P) < 0
Hence W = 0 (negative)

Reason:
A small positive charge moving from Q (farther) to P (closer) is moving against the direction of the electric field. Hence the field does negative work on it (external agent must do positive work).

💬 Doubts & Comments

Abhi tak koi comment nahi

Apna comment likhein

💬 Doubts & Comments

Abhi tak koi comment nahi

Apna comment likhein

🔔 Email Updates Lein