How Does a Transformer Change Voltage and Current?
What happens to the current when a transformer changes the voltage from 120 V to 12000 V?
(a) Stepped up by a factor of 100
(b) Stepped down by a factor of 100
(c) Neither stepped up nor stepped down
Answer:
The current delivered by the wall socket is stepped down by a factor of 100.
A transformer changes the 120-V at a wall socket to 12000 V. The current delivered by the wall socket is:
A transformer changes the 120-V at a wall socket to 12000 V. The current delivered by the wall socket is:
To determine the effect on the current, we need to consider the transformer's voltage step-up factor. The voltage step-up factor can be calculated as follows:
Voltage step-up factor = Secondary voltage (output voltage) / Primary voltage (input voltage)
In this case, the primary voltage is 120 V, and the secondary voltage is 12000 V. Therefore, the voltage step-up factor is:
Voltage step-up factor = 12000 V / 120 V = 100
Now, transformers follow the principle of power conservation, which means the input power is equal to the output power (ignoring energy losses). The power equation is:
Power (P) = Voltage (V) × Current (I)
Since input power equals output power, we have:
Primary voltage × Primary current = Secondary voltage × Secondary current
We can rearrange this equation to find the relationship between primary and secondary current:
Primary current / Secondary current = Secondary voltage / Primary voltage
Plugging in the values:
Primary current / Secondary current = 100
This means that the primary current (current delivered by the wall socket) is 100 times larger than the secondary current.
Therefore, the correct answer is:
(b) The current delivered by the wall socket is stepped down by a factor of 100.
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