1. A 4.5-cm tall butterfly lands 65 cm in to the left of a converging lens of focal length of magnitude 25 cm. What can you say about the image that is formed?
The image is virtual, 2.5 cm tall, 30 cm on the right side of the lens.
The image is virtual, 2.8 cm tall, 41 cm on the left side of the lens
The image is virtual, 2.0 cm tall, 15 cm on the right side of the lens.
The image is real, 4.5 cm tall, 65 cm on the left side of the lens.
The image is real, 2.8 cm tall, 41 cm on the right side of the lens.
2. A Nd:YAG laser has a wavelength of 1064 nm in air. It enters some diamond with an index of refraction of 2.42. What can you say about the wavelength of the light in the diamond?
2600 nm
100 nm
440 nm
530 nm
1060 nm
3. A Ti:Sapphire laser has a wavelength of 1200 nm and a pulse of duration 12 fs. If the total energy of the pulse is 2.4 J how many photons are emitted in one pulse?
3.2 × 1017
1.45 x 1019
1.6 × 1017
9.9 × 1019
4.8 × 1019