Physicshard · Past Paper
A concave mirror has a radius of curvature of 40 cm. To get an image twice the size of the object, the object distance should be:
A10 cm or 30 cm
B20 cm or 60 cm
C15 cm or 45 cm
D30 cm only
✓ Correct Answer: A — 10 cm or 30 cm
f = -20. m = f/(f-u). If m=2 (virtual), u=-10. If m=-2 (real), u=-30.
Share this question
More from Physics
- Calculate the equivalent resistance of two 4 Ohm resistors connected in parallel.
- The refractive index of a medium is 1.5. The speed of light in that medium is:
- Light of wavelength 6000 Angstroms in air enters a medium of refractive index 1.5. What is the wavelength in the medium?
- Periscope works on the principle of:
- The resistivity of a wire depends on its: