An electromagnet is created using a battery, an insulated copper wire and an iron nail. the wire is wrapped around the nail 20 times and attached to the battery. which pair of changes will definitely increase the strength of the electromagnet?
a) increase the voltage of the battery and decrease the number of turns of the coil.
b) decrease the voltage of the battery and decrease the number of turns of the coil.
c) increase the voltage of the battery and increase the number of turns of the coil.
d) decrease the voltage of the battery and increase the number of turns of the coil.

The strength of the electromagnet will be increased with increase in the voltage of the battery and increase in the number of turns of the coil.

Option C

Explanation:

An electromagnet is generated by passing current through a magnetic material. As per Faraday’s law, magnetic field will be maintained till there is presence of electric flux in the circuit. Thus, like a solenoid, the number of turns of the copper wire on the iron nail will be directly proportional to the strength of the electromagnet.

This is because each turn of the copper wire will act a small region of electromagnet which when added up will lead to increase in the strength of the electromagnet. Similarly,  the electromagnet's strength will also increase when the current flowing in the solenoid is increased.

As the current flow in a circuit is proportional to the battery's voltage used, the increase in the voltage will lead to increase in the flow of current in the solenoid structure. Thus, the increase in voltage as well as the coil's turn number leads to increase in the electromagnet's strength.

not really sure but thinking 1.54 mm/us

think about the oscillation of the toy shown in the video. when the toy is at the highest point of its motion, its velocity is zero and its acceleration is negative.