Question

Need help with these, thank you!

True Story: A certain farmer was protesting eminent domain being used to put an electric power line in his field. The farmer placed a coil containing several hundred turnings of copper wire near, but not touching the power line. He was able to steal some electrical power from the line even though his coil was not touching the power line. Which of the following statements is true regarding this situation?

	A.	This method of pilferage would work for both AC (alternating current) and DC (direct current) electricity.
	B.	This method of pilferage only works for DC electricity.
	C.	This method of pilferage only works for AC electricity.
	D.	This method of pilferage does not work for AC or DC electricity.

On a clear day, the intensity of solar radiation is about 1000 W/m². A typical solar panel has an efficiency of 25%, meaning that 25% of the incoming solar energy gets converted to electrical energy. A typical suburban house might consume 1 kW of electrical energy. Roughly, how many square meters of solar cells would be required to supply this suburban home with solar-produced electricity?

	A.	¼ m2
	B.	1 m2
	C.	4 m2
	D.	25 m2

Consider a BNSF freight train hauling the clay, montmorillonite, up the El Cajon pass. This particular train usually hauls 150 hopper cars at a constant speed of 25 mi/hr. Suppose that the engineer decides to run the train at 50 mi/hr. Which of the following statements most accurately describes the change in the amount of diesel consumed?  

Hint: Think about kinetic energy. Where does that kinetic energy come from? I sure hope the brakes work well....

	A.	There is no change in the amount of fuel consumed.
	B.	The amount of fuel consumed doubles.
	C.	The amount of fuel consumed quadruples.
	D.	It is not possible to make any conclusion whatsoever since we do not know the mass of the train.

A mirage is an optical illusion that is due to which physical property or phenomena?

	A.	The fact that light changes speed in air due to changes in the temperature of the air.
	B.	The Doppler effect.
	C.	The fact that light changes direction when there is a difference in the refractive index.
	D.	Both A and C are correct.

Answer 1

PROBLEM 1:

The change in electric current can be used to create another changing electric current using conducting coils termed as electromagnetic induction.

Since DC currents are constant and do not change with time, we can not create current using DC power.

So, the correct option is

C: This method of pilferage only works for AC electricity.

PROBLEM 2:

The intensity of the radiation is

The efficiency of solar panel is 25%, SO, the electrical power generated by solar panel per square meter is

Total power required is 1kW = 1000 W. So, the area of the solar panel required is

So, the correct option is

C: 4 m².

PROBLEM 3:

The initial energy of the train is

And the new energy of the train is

We have

So, the new energy is

The energy of the train is quadrupled, So, the fuel consumption is also quadrupled.

So, the correct option is

C: The amount of fuel consumed quadruples.

PROBLEM 4:

A mirage is an optical illusion that is due to

The fact that light changes speed in the air due to changes in the temperature of the air.

The fact that light changes direction when there is a difference in the refractive index.

So, the correct option is

D: Both A and C are correct.