Question

Radiation, with wavelength 6561 A° falls on a metal surface to produce photoelectron. The electrons are made to enter a uniform magnetic field of 3×10-4 T. If the radius of the circular path fallowed by the electron in 10 mm. The work function of metal is close to.​

Answer 1

Given:

1. Wavelength = 6561 Å

2. Magnetic field = 3 × 10⁻⁴ T

3. Radius = 10mm

To find:

The work function of the metal

Solution:

• Let the work function be denoted by ϕ.

• We know that, K.E = (hc/λ) - ϕ

• Also, R = √[2mKE / qB]

                    = √[2m((hc/λ) - ϕ) / qB]

• Therefore, R²q²B²/2m = (hc/λ) - ϕ

                                          ϕ = hc/λ - R²q²B²/2m

                                          ϕ = 1.0899eV

• Thus, the work function of the metal is close to 1.1eV.