Wave behaviour

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Question 38
Medium

An optical device uses a convex lens to project an image of an object onto a screen.

a.

The diagram shows one light ray as it passes from the top of the object through the thin convex lens on a grid:

A ray diagram on a grid. The horizontal axis is the principal axis of a convex lens. The vertical axis at 0 represents the thin convex lens. The focal points F are located at 2 units to the left (-2) and 2 units to the right (+2) of the lens. An object, represented by a vertical arrow of height 2 units pointing upwards, is located 3 units to the left of the lens at position x = -3. A single ray is drawn starting from the top of the object at (-3, 2), traveling horizontally to the lens at (0, 2), and then refracting downwards through the focal point F on the right at (2, 0) and continuing to the right.

Describe how to draw one more standard ray from the top of the object to locate where the image is formed, and state the position (horizontal and vertical coordinates) where the image's top is formed if the optical center of the lens is at (0,0)(0,0)(0,0).

[2]
b.

State two characteristics of the image formed.

[2]
c.

The light source inside the device produces white light. Explain how this source can be used to obtain blue light.

[2]
d.

The device is connected to the standard UK mains power supply. State the potential difference between the live wire and the earth wire in normal use.

[1]
e.

An appliance with a metal outer casing needs an earth wire. An appliance with a plastic outer casing does not. Explain why.

[2]

Wave behaviour Questions

  1. GCSE
  2. /Physics
  3. /Wave behaviour