Magnetism
What causes the magnetic field around a bar magnet?
Its atomic structure- iron atoms are aligned in the same direction.
What is a transverse wave? Give an example
Vibration at right angles
Example: water, light
What is the difference between concave and convex?
Concave is a shape that is curved inwards, and convex is a shape that is curved outwards.
A wave completes 4 cycles each second. If the wave travels 20m in 1 second, what is the wavelength?
5 meters
What is the name for a wire coil with a piece of iron inside the coil?
Electromagnet
What is the shape of a magnetic field around a current-carrying wire?
Concentric circles
What is a longitudinal wave? Give an example
Compressional wave
Example: sound
What accounts for the few minutes of sunlight before sunrise and after sunset?
Refraction. (At the horizon line, light refracts to appear above the horizon even if the sun is below the horizon)
What is the frequency of a sound traveling at 340 m/s with a wavelength of 7 m?
48.57 Hertz
What do polarizing sunglasses do?
Only allow vertical light waves to reach your eyes, so horizontal light waves (reflected light) gets blocked
How should you position a current-carrying wire in a magnetic field to create the strongest force?
Wire perpendicular to the magnetic field
What is an echo?
The reflection of sound
What is the Law of Reflection?
angle of incidence=angle of reflection
A transformer produces 500 V from a 150 primary voltage with 30 primary turns. How many secondary turns do there need to be?
100 turns
What is the period of a sound with a frequency of 5 Hz?
1/5 second
What is the difference between an electric motor and an electric generator?
An electric motor converts electrical energy into work. An electric generator converts work into electrical energy.
What is the fundamental wave relationship?
velocity of wave= wavelength x frequency
What is refraction?
Bending of a ray of light/changing of the speed of light when it passes from 1 transparent medium to another
If radio waves travel at a speed of 3 x 10^8 m/s, how many minutes would it take to travel a distance of 8.9 x 10^11 meters?
49.44 minutes
Explain how the north and south poles of a magnet are like heads and tails on a coin
They are inseparable; if you have one you will have the other
If you want to decrease voltage using a transformer, should you increase or decrease output loops?
Decrease
Order these waves from longest to shortest wavelength: visible light, microwaves, x rays
microwaves, visible light, x rays
If you walk towards a mirror at a certain speed, the relative speed between you and your image is:
Twice your speed
A convex lens has a focal length of 6 cm. If an object is placed 18 cm from the lens. How far from the lens is the image?
9 cm
Why is the sky blue?
Blue light is scattered more in the Earth's atmosphere than other colors because it is shorter, smaller waves