Question

A 12 V source is connected across a 10 resistor.

(a) How much energy is used in two minutes?

(b) If the resistor is disconnected after one minute, is the power during the first minute greater than, less than, or equal to the power during a two minute interval?​

Answer 1

Answer:

(a) “Every two minutes, the energy reaching the earth from the sun is equivalent to the whole annual energy use of humanity. All the energy … the cars, lighting, and air conditioning of the world … in one year is equivalent to two minutes of the sun,” said Dr Lamya N.

Answer 2

Zero watts of energy is used in two minutes and the power during the first minute is greater than the power during a two minutes interval

Given:

Energy = 12V

Source = 10

To find:

(a) How much energy is used in two minutes?

(b) If resistor is disconnected after one minute, is the power during the first minute greater than, less than, or equal to the power during a two-minute interval?​

Solution:

According to the Ohm's Law -

Volts = current x resistance.

Consequently, within the first minute after connecting the voltage source, current flows through the resistor as

12v / 10

= 1.2 amperes.

Therefore,

1.2 amperes x 12 volts

= 14.4 watts,

Thus, 14.4 watts are delivered in one minute.

Now, similarly in the second minute -

0  x 12

= 0 watts.

Thus, 14.4 watts in the first minute, 0 watts in the second minute.

Answer: Zero watts of energy is used in two minutes and the power during the first minute is greater than the power during a two minutes interval

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