8 A voltage of 3.0 V is required to operate an alarm circuit. Only a 12 V supply is available, together with a number of resistors. The resistance of the alarm circuit is about 1000 Ω. A student selects four resistors of value 10 kΩ and sets them up in a series circuit. The voltmeter indicates a potential drop across each resistor of 3.0 V. However, as soon as the alarm circuit is connected, the potential drops to near zero. a Comment on why this happens. b Check the student’s calculations. c Should the student have selected resistors of higher or lower value?