1.
A girl looks into a bathroom mirror to brush her hair. The figure shows what she sees in the mirror.
On which hand is she holding the brush?
Correct Answer
A. Right hand
Explanation
Based on the figure shown in the mirror, the girl appears to be holding the brush with her right hand.
2.
What causes refraction when light travels from air into glass?
Correct Answer
D. The speed of the light changes.
Explanation
When light travels from air into glass, it undergoes refraction because the speed of light changes. Refraction occurs when light passes from one medium to another with a different optical density, causing the light waves to bend. In this case, the glass has a higher optical density than air, causing the speed of light to decrease as it enters the glass. This change in speed results in the bending of light, which is known as refraction. The other options (amplitude, color, and frequency) do not directly affect refraction in this scenario.
3.
The diagram shows a ray of light entering a block of glass.Which numbered angles are the angles of incidence and of refraction?
Correct Answer
D. Incidence:2; refraction: 4
Explanation
The diagram shows a ray of light entering a block of glass. The angle of incidence is the angle between the incident ray and the normal to the surface of the glass. In this case, angle 2 is the angle of incidence. The angle of refraction is the angle between the refracted ray and the normal to the surface of the glass. In this case, angle 4 is the angle of refraction.
4.
Which diagram correctly shows a ray of light passing through a rectangular glass block?
Correct Answer
A. A
Explanation
Diagram A correctly shows a ray of light passing through a rectangular glass block. The ray of light enters the block at an angle, bends towards the normal, and then exits the block at an angle away from the normal. This is the correct behavior for light passing through a rectangular glass block. Diagrams B, C, and D do not accurately represent the bending of light as it passes through the block.
5.
Light from the Sun passes through a prism and a spectrum is produced on a screen.
A thermometer placed at P shows a large temperature rise.
Which type of radiation causes this?
Correct Answer
A. Infra-red
Explanation
When light from the Sun passes through a prism, it is separated into its component colors, producing a spectrum on the screen. The different colors of the spectrum correspond to different wavelengths of light. In this scenario, if a thermometer placed at P shows a large temperature rise, it indicates that the type of radiation causing this is infra-red. Infra-red radiation has longer wavelengths than visible light and is associated with the heating effect. Therefore, it is the most likely type of radiation causing the temperature rise in this situation.
6.
The diagram shows a ray of light incident on the edge of a piece of glass. The angle i is bigger
than the critical angle.
Which arrow correctly shows the direction of the ray after it leaves the edge of the glass?
Correct Answer
D. D
Explanation
The correct answer is D because when the angle of incidence is greater than the critical angle, total internal reflection occurs. This means that the light ray is reflected back into the glass instead of refracting out of it. Therefore, the arrow in option D correctly shows the direction of the ray after it leaves the edge of the glass.
7.
A man sees a stone at the bottom of a pool of water.
Which path could be taken by light from the stone to the man?
Correct Answer
B. B
8.
A ray of light passes from air into a block of glass with an index of refraction of 1.5. The angle of incidence is 30 degrees.
Calculate the angle of refraction.
Correct Answer
B. 19.5
Explanation
When light passes from one medium to another, it bends or refracts. The angle of refraction is the angle between the refracted ray and the normal to the surface of the medium. In this case, the light is passing from air into a block of glass with an index of refraction of 1.5. The angle of incidence is given as 30 degrees. Using the formula for calculating the angle of refraction, which is given by Snell's law (n1*sin(theta1) = n2*sin(theta2)), where n1 and n2 are the indices of refraction of the two media, and theta1 and theta2 are the angles of incidence and refraction respectively, we can substitute the values given in the question to calculate the angle of refraction as 19.5 degrees.
9.
The speed of light in air is almost 3x108 m/s. In one piece of glass, light slows down to 2x108 m/s. What is the index of refraction for the glass?
Correct Answer
C. 1.5
Explanation
The index of refraction for a material is a measure of how much the speed of light is reduced when it passes through that material. In this case, the speed of light in air is given as 3x10^8 m/s and in the glass it slows down to 2x10^8 m/s. To find the index of refraction, we can divide the speed of light in air by the speed of light in the glass: 3x10^8 m/s / 2x10^8 m/s = 1.5. Therefore, the index of refraction for the glass is 1.5.
10.
In an optics lesson, a Physics student traces the paths of three rays of light near the boundary
between medium A and air. The student uses a protractor to measure the various angles.
State the critical angle of medium A
Correct Answer
D. 43
Explanation
The critical angle of a medium is the angle of incidence at which the angle of refraction becomes 90 degrees. In this case, the correct answer is 43. This means that when light travels from medium A to air, if the angle of incidence is greater than 43 degrees, total internal reflection will occur.