Refraction and Optics
What phenomenon causes a straw in a glass of water to appear bent?
Refraction
Which type of lens is used to correct nearsightedness?
Concave lens
What material is most likely to be attracted to a magnet?
Iron
What increases the strength of an electromagnet?
Adding more coils or increasing the current
What type of electromagnetic force is used in maglev trains?
Electromagnetic repulsion
What type of lens is used in a magnifying glass?
Convex lens
What role do prisms play in binoculars?
To invert and correct the orientation of the image
What term describes materials that are strongly attracted to magnets?
Ferromagnetic materials
What principle explains the induction of current in a coil of wire?
Electromagnetic induction
How does a loudspeaker produce sound?
Interaction between an electromagnet and a permanent magnet moves the cone
Which part of the human eye functions similarly to a camera lens?
Lens
Why do objects appear larger when viewed through a convex lens?
Because the convex lens converges the light rays
Why do two north poles of bar magnets repel each other?
Because like poles repel
What is the relationship between the number of loops in a coil and the induced EMF?
The induced EMF doubles if the number of loops doubles
Why are magnetic materials used in hard drives?
They can be easily magnetized and demagnetized
What principle explains the dispersion of light into a rainbow?
Dispersion
What type of lens is used to correct farsightedness?
Convex lens
What happens to a nail when it is placed next to a magnet?
It becomes magnetized
What law states that the direction of the induced current opposes the change in magnetic flux?
Lenz’s Law
What principle allows transformers to operate effectively?
Electromagnetic induction
How does light behave when it hits a smooth, reflective surface?
Reflection
Which part of the eye adjusts the focus of light onto the retina?
Lens
Which materials are likely to be attracted by a magnet: iron, wood, plastic, or cobalt?
Iron and cobalt
What happens to the induced current if the speed of the changing magnetic field increases?
The current increases
How do MRI machines generate images of the human body?
By using strong magnetic fields