Question

Faradays Electromagnetic Lab – AC/DC Current and Electromagnetism
Electromagnet

1. What happens to the speed of the current as you adjust the voltage?



2. What happens to the magnetic field as you adjust the number of loops?



3. What happens to the magnetic field when you switch to AC voltage?




Transformer

1. Why doesn’t the transformer work with DC voltage?





2. What five things can you adjust to get the highest maximum voltage?




Generator

1. What does RPM stand for?




2. What four things can you adjust to get the highest maximum voltage?

Answer 1

Faradays Electromagnetic lab:

1) What happens to the speed of the current as you adjust the voltage?

ans.) From Ohm's Law, we know that current is directly proportional to voltage.

V=IR.

So, current varies directly with respect to voltage. If voltage is increased, current also increases. If voltage is decreased, the value of current also decreases. Provided the resistance of the circuit is constant.

2.What happens to the magnetic field as you adjust the number of loops?

ans.) When a wire is wound around a coil, a static magnetic field is produced making it forming a shape of a bar magnet. When current is flowing through the coil, magnetic flux is produced around the coil. The magnetic flux produced directly depends upon the current flowing. Now, if we increase the number of turns around the coil, with the same amount of current flowing in the coil, then the magnetic field strength is increased. Hence, increasing the number of turns in the coil will increase the magnetic field strength.

3. What happens to the magnetic field when you switch to AC voltage?

ans.) Magnetic field can be produced in any current carrying conductor whether it is A.C or D.C.

Now, if you consider an A.C circuit, it will also produce a magnetic field. Since,the supply is A.C i.e., alternating current we have positivee and negative half cycles of current. So, the magnetic field produced will also be changing according to the direction of the current flow. Hence, magnetic field will be lost. SO, the magnetic field strength is weak when compared with the D.C circuit.

Transformer:
1. Why doesn’t the transformer work with DC voltage?

ans.) working of transformer depends upon Faradays law of electromagnetic induction.

"A changing magnetic field will induce an emf in a circuit."

So, to induce voltage in a loop of wire, we require a changing magnetic field. That changing magnetic field is only produced by an A.C supply. But, if you consider a D.C voltage, the current is constant and hence the magnetic field is constant. As there is no changing magnetic field, no output voltage is produced.

2. What five things can you adjust to get the highest maximum voltage?

ans.) The five things we can adjust to get highest maximum voltage in a transformer are:

1) Operating at higher frequencies.

2) Reducing magnetizing effect which reduces hysterisis loss,

3) increasing transformers capacity.

4) Shell form design of the transformer is more advantageous.

5) Laminating the cores for reducing the losses.

Generator

1. What does RPM stand for?
ans.) Revolutions per minute.

2. What four things can you adjust to get the highest maximum voltage?

ans.) The four things to adjust to get the highest voltage are:

1) Magnetic field strength should be increased.

2) Number of turns in the coil should be increased.

3)Increase the area of the coil.

4) Increase the speed of revolutions(RPM)