33. (a) (i) Explain the following statements giving reason : (I) An equipotential surface through a point is normal to the electric field at that point. (II) When a dielectric is placed in an external electric field, the electric field inside the dielectric is less than that outside it. (III) The potential difference between the plates of a charged parallel plate capacitor decreases when its plates are brought closer. (ii) Obtain an expression for the work done to dissociate the system of three charges $q$, $-4q$ and $2q$ placed at the vertices $A$, $B$ and $C$ respectively of an equilateral triangle of side '$a$'. OR (b) (i) Answer the following giving reason : (I) The electron drift speed is estimated to be only a few $\text{mm/s}$ for currents in the range of a few amperes. How, then, is the current established almost the instant a circuit is closed ? (II) A low voltage supply from which one needs high currents must have very low internal resistance. Why ? (III) The assertion that $V = IR$ is a statement of Ohm's law is not true. Why ?

Year	Paper Code	Set	Position
CBSE 2026	Series 55-4	Set 1	Question 33
CBSE 2026	Series 55-4	Set 2	Question 31
CBSE 2026	Series 55-4	Set 3	Question 32

• Step 1: Stating the fundamental formula / law statement (+1 Mark)
• Step 2: Intermediate mathematical substitution or proof steps (+1 Mark)
• Step 3: Correct final value or conclusion with mandatory SI units (+1 Mark)