#### minimeeeeeee

##### Full Member
10+ Year Member
I was doing practice tests on TopScore and did not know how to solve

1. A uniform 25-kg board is 12-m long and has a 50-kg weight attached to one end. How far from the weight will be the center of gravity of this system? (Answer: 2 m)

2. In AC series circuit the capacitive reactance is 100 ohms and frequency is 50 Hz. What is the capacitance? (Answer: 32 x 10^-6 farads)

3. A soap bubble film of index of refraction 1.5 is illuminated by light of wavelength 400 nm. FOr what thickness of the soap film, other than the minimum thickness, will constructive interference occur? (Answer: 200 nm)

4. A 4 cm tall object is placed along the principal axis of a thin converging lens with a focal length of 30 cm. If the object distance is 50 cm, which of the following describes the image distance and height, respectively? (Answer: 75 cm and 6.0 cm)

5. How many possible substrates are available for the hydrogen atom when the principal quantum number is 4? (Answer: 32)