Image formation and magnificationEdexcel A-Level Physics: Flashcards

What these 14 flashcards ask

State the lens equation.
What does the real-is-positive convention say about signs?
What does a negative value of v tell you?
Give the formula for linear magnification.
What is a real image?
What is a virtual image?
When does a converging lens form a real image?
When does a converging lens form a virtual image?
Is a real image from a single lens upright or inverted?
Is a virtual image from a single lens upright or inverted?
How does a magnifying glass work?
Which way must a camera lens move for a closer object?
What are the gradient and intercepts of a graph of 1/v against 1/u?
A lens gives 1/v = 4.0 m⁻¹. What is v?

Exam questions on Image formation and magnification

A slide projector uses a thin converging lens of focal length 0.100 m. A slide, 24 mm wide, is placed 0.120 m from the lens on the principal axis, and a sharp image is formed on a distant screen.
Calculate the width of the image on the screen.2 marks
A student uses a thin converging lens of focal length 0.060 m as a magnifying glass. She holds an insect specimen 2.0 mm long on the principal axis, 0.045 m from the lens, and views it through the lens from the other side.
Calculate the length of the image of the specimen.2 marks
A camera lens of focal length 0.050 m is used to photograph a person who is 1.80 m tall and standing 4.0 m from the lens. The light-sensitive sensor is placed behind the lens at the position where a sharp image forms.
Calculate the distance from the lens to the sensor.3 marks

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).