Question
42- A student measures the potential difference across a device and the current in the device.
Which calculation gives the resistance of the device?
A current + potential difference
B current
potential difference
C) potential difference
current
D potential difference
current
43- A water heater is connected to a 230 V supply and there is a current of 26 A in the heater. It takes 20 minutes to heat the water to the required temperature.
29.0625/21/M/J/18
How much energy is supplied by the heater?
A
B
C
D
A current + potential difference
B current
C) potential difference
43- A water heater is connected to a 230 V supply and there is a current of 26 A in the heater. It takes 20 minutes to heat the water to the required temperature.
29.0625/21/M/J/18
A
B
C
D
Ask by Luna Barker. in Egypt
Jan 25,2025
Upstudy AI Solution
Tutor-Verified Answer
Answer
Question 42:
To find the resistance, divide the potential difference by the current.
Answer: C) Potential Difference Current
To find the resistance, divide the potential difference by the current.
Answer: C) Potential Difference
Question 43:
Calculate energy using power and time.
Answer: D)
Calculate energy using power and time.
Answer: D)
Solution

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Mind Expander
To find the resistance of the device, you should use Ohm’s Law, which states that resistance ® can be calculated by dividing the potential difference (V) by the current (I). Therefore, the correct option is C) potential difference
current.
Now, for the water heater question, you can calculate the energy supplied by the heater using the formula
. Here, V is the voltage (230 V), I is the current (26 A), and t is the time in seconds (20 minutes = 1200 seconds). When you compute this, you’ll find the energy supplied is
, which corresponds to option D.