4 questions · 4 marks · ≈ 4 min
An electric heater and an electric motor are connected to a mains power supply.
The power of the heater is 3.0 kW and the power of the motor is 1.0 kW.
The cost of electricity is $0.20 per kWh.
What is the total cost of using the heater and the motor for 5.0 hours?
Choose your answer
$0.12
$0.16
$3.00
$4.00
An electric heater and an electric motor are connected to a mains power supply.
The power of the heater is 3.0 kW and the power of the motor is 1.0 kW.
The cost of electricity is $0.20 per kWh.
What is the total cost of using the heater and the motor for 5.0 hours?
Choose your answer
$0.12
$0.16
$3.00
$4.00
A quantity is defined as 'the electrical work done by a source in moving a unit charge around a complete circuit'.
What is the quantity?
Choose your answer
electric current
electromotive force (e.m.f.)
potential difference (p.d.)
resistance
Table 9.1 gives some data about five substances.
Table 9.1
| aluminium | ethanol | poly(ethene | sulfur | water | |
|---|---|---|---|---|---|
| density in g / cm3 | 2.7 | 0.8 | 0.9 | 2.0 | 1.0 |
| state at 25 °C | solid | liquid | solid | solid | liquid |
| electrical property | conductor | insulator | insulator | insulator |
State the electrical property of poly(ethene)
Give a reason for your answer.
electrical property: ..................
reason: ..................