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Fig shows the electric field lines due to a point positive charge. P and Q are two point in the electric field. i) What is the sign pf V_(P)-V_(Q)? ii) What is the sign of the potential energy difference of a small negative charge between Q and P? iii) What is the sign of work done by the field in moving a small positive charge from Q to P? iv)What is the sign of work done by external agent in moving a positive charge from Q to P? |
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Answer» <P> Solution :(i) Potential at point `V prop 1//r`. Therefore, `V_(P) gt V_(Q)`.Hence sign of `V_(P)-V_(Q)` is positive. (ii) If a negative CHARGE is placed at Q, it will move towards P. SINCE, a charge moves from higher potential ENERGY to lower potential energy, `U_(Q) gt U_(P)`. Therefore, `U_(Q)-U_(P)` is positive. (iii) If a small positive charge is placed at P, work done by the field in moving it to Q is positive. Hence, work done by the field in moving small positive charge from Q to P is negative. (iv) Since in moving the positive charge from Q to P, external AGENT should do work against the field, the work done is positive. |
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