An object is placed 60 cm from a convex lens of focal length 15 cm. How far from the lens is the image?
Answer and explanation
Correct answer: A. 20 cm
- Step 1: Lens formula: 1/f = 1/u + 1/v (real-is-positive). Step 2. 1/v = 1/15 − 1/60, so v = 20 cm. Answer: 20 cm. Why not the others: 12 cm is what you get if you use 1/v = 1/f + 1/u. 45 cm is what you get if you subtract the distances. 75 cm is what you get if you add the distances.
Practise more Electricity, Magnetism and Atomic Physics.
Free questions with an explanation for every one, and full timed MDCAT Pakistan mock tests.
More Electricity, Magnetism and Atomic Physics questions
- A 4 μF capacitor is charged to 6 V. How much charge does it store?
- A wire 0.2 m long carries 2 A at right angles to a magnetic field of 0.5 T. What force acts on it?
- A transformer has 100 turns on the primary coil and 2000 turns on the secondary. The primary voltage is 230 V. What is the secondary voltage…
- A body moves in a circle of radius 50 m at 10 m/s. What is its centripetal acceleration?
- A stone is dropped from a height of 125 m. How long does it take to reach the ground? (take g = 10 m/s²)
- A body of volume 0.001 m³ is fully immersed in a liquid of density 1200 kg/m³. What is the upthrust? (take g = 10 m/s²)