A light wave has a wavelength of 420nm, calculate the energy of this wave in joules.

E = hfE = energyh = planck's constant = 6.63 x 10-34f = wave frequency
c = fλf = c/λ
E = hc/λ
c = 3.0 x 108 The speed of light which in this case is the speed of the wave.λ = 420 x 10-9 As 1nm = 1 x 10-9m
E = ((6.63 x 10-34)x(3.0 x 108))/(420 x 10-9)E = 4.74 x 10-19J leaving the answer as this is in Joules already.

ND
Answered by Nicholas D. Physics tutor

6626 Views

See similar Physics A Level tutors

Related Physics A Level answers

All answers ▸

Calculate the threshold frequency for a metal with a work function of 3eV


A car of mass m is travelling at a speed v around a circular track of radius r banked at an angle θ. (a) What is the centripetal acceleration of the car? (b) What is the normal force acting on the car? (c) If θ = 45°, r = 1 km what is the maximum speed?


How would you explain general relativity?


A ball is kicked off a cliff at a height of 20m above ground and an angle of 30 degree from the horizontal, it follows projectile motion and lands after a time t. Its velocity at the maximum height it reaches is 20m/s, how long does it take it to land?


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning