Parallel resistors increase total current when switch closes

Steps:

• Switch open: only R in circuit, so emf E = 4R (X reads 4 A).
• Switch closed: R parallel with 2R, equivalent resistance = (R × 2R)/(3R) = (2/3)R.
• Total current on X: E / (2R/3) = 4R / (2R/3) = 6 A.
• Current on Y (through 2R branch): E / 2R = 4R / 2R = 2 A.

Why C is correct:

• Option values match ohm's law application in parallel circuits: total current rises to 6 A, with 2 A through the 2R path due to voltage division.

Why the others are wrong:

• A: X stays 4 A, but parallel path lowers resistance, raising total current.
• B: X stays 4 A (wrong, as above); Y 2.7 A mismatches E/2R = 2 A.
• D: X 6 A correct, but Y 4 A implies meter in R branch, not 2R.

Final answer: C