Engineering Board Exam Reviewer · Physics · hard
Light of wavelength 400 nm falls on a metal with a work function of 2.3 eV. What is the maximum kinetic energy of the ejected photoelectrons? (h = 6.626 × 10-34 J· s, c = 3 × 108 m/s, 1 eV = 1.602 × 10-19 J)
- 0.80 eV
- 3.10 eV
- 5.40 eV
- 0.00 eV
Answer
A. 0.80 eV
Solution
Photon energy = hc/ = 3.10 eV. KE max = hf - = 3.10 - 2.3 = 0.80 eV.
More Physics questions
- What is the energy of a photon with a wavelength of 500 nm? (h = 6.626 × 10-34 J· s, c = 3 × 108 m/s)
- A series RL circuit has R = 30 and XL = 40 . What is the power factor?
- A series RL circuit has R = 30 and XL = 40 connected to a 220 V AC supply. What is the current?
- What is the resonant frequency of a series LC circuit with L = 10 mH and C = 1 F?
- What is the capacitive reactance of a 100 F capacitor at 60 Hz?
- What is the inductive reactance of a 0.1 H inductor at 60 Hz?
- An ideal step-down transformer converts 220 V to 22 V. If the secondary current is 10 A, what is the primary current?
- A transformer has 500 primary turns and 50 secondary turns. If the primary voltage is 220 V, what is the secondary voltage?
- A 0.5 m conductor moves at 10 m/s perpendicular to a 0.4 T magnetic field. What emf is induced across its ends?
- A solenoid 0.5 m long has 1000 turns and carries 2 A. What is the magnetic field inside it? ( 0 = 4π × 10-7 T· m/A)