The diagram depicts a circuit that includes a d.c. power supply, a motor and a variable resistor. Three ammeters, X, Y and Z, indicate the current in separate parts of the circuit. Ammeter X has a reading of 4.0 A. Which statement is correct?
- AThe readings on Y and Z are both less than 4.0 A.
- BThe readings on Y and Z are both equal to 4.0 A.
- CThe readings on Y and Z are both greater than 4.0 A.
- DThe reading on Z is zero.