Regents Physics 5

Question 1

A photon has a frequency of 6.0 × 10¹⁴ Hz. What is its energy? (h = 6.63 × 10⁻³⁴ J·s)

Accepted Answer

3.98 × 10⁻¹⁹ J

Answer

E = hf = (6.63 × 10⁻³⁴)(6.0 × 10¹⁴) ≈ 3.98 × 10⁻¹⁹ J.

Question 2

A spring with spring constant k = 200 N/m is compressed 0.05 m. What is the elastic potential energy stored?

Accepted Answer

0.25 J

Answer

PE = ½kx² = ½(200)(0.05)² = ½(200)(0.0025) = 0.25 J.

Question 3

In the photoelectric effect, increasing the intensity of incident light (at constant frequency) causes:

Accepted Answer

More electrons to be emitted per second

Answer

Greater intensity means more photons per second, each ejecting one electron, so the emission rate increases but individual electron energy does not.

Question 4

Two resistors of 6 Ω each are connected in parallel. What is the equivalent resistance?

Accepted Answer

3 Ω

Answer

For two equal resistors in parallel: R_eq = R/2 = 6/2 = 3 Ω.

Question 5

A standing wave is formed on a string. The distance between two adjacent nodes is 0.4 m. What is the wavelength?

Accepted Answer

0.8 m

Answer

Adjacent nodes are separated by half a wavelength, so λ = 2 × 0.4 = 0.8 m.

Regents Practice Test