28. Maria makes an electromagnet shown in the figure below. The battery has a voltage of 6.0V, and she uses an iron nail. Which of the following would increase the strength of the magnetic field produced?

Question

a
Doubling the number of times the wire wraps around the nail.
b
Replacing the iron nail with one made of plastic.
c
Reversing the direction of the current flow.
d
Changing the battery to a 3.0V battery.

29. What causes hot air to rise from the pavement on a hot summer day?
A) conduction
B) convection
C) radiation
D) insulation

30. What type of energy transformation is occurring when a lamp is plugged into an outlet?

a
electrical to mechanical
b
electrical to light
c
mechanical to electrical
d
chemical to light

Answer 1

28. The correct answer is:
a) Doubling the number of times the wire wraps around the nail.
Increasing the number of wire turns around the nail increases the strength of the magnetic field produced by the electromagnet.

29. The correct answer is:
B) convection.
Hot air rises due to convection, as warm air is less dense than cooler air and moves upwards.

30. The correct answer is:
b) electrical to light.
When a lamp is plugged into an outlet, electrical energy is transformed into light energy (and also some heat energy).