WAEC Physics questions: Elementary modern physics

11 questions with answers and explanations. Tap an option to check yourself.

1. Question 1· Elementary modern physics· WAEC

   Which radiation is stopped by a thin sheet of paper?

   • Abeta particles
   • Bgamma rays
   • Calpha particles
   • DX-rays

   Show answer

   Explanation and discussion

2. Question 2· Elementary modern physics· WAEC

   A radioactive sample has a half-life of 5 days. What fraction of it remains after 15 days?

   • A1/8
   • B1/3
   • C1/6
   • D1/16

   Show answer

   Explanation and discussion

3. Question 3· Elementary modern physics· WAEC

   Which radiation is the most penetrating?

   • Abeta particles
   • Balpha particles
   • Cgamma rays
   • Dcathode rays

   Show answer

   Explanation and discussion

4. Question 4· Elementary modern physics· WAEC

   Alpha particles are

   • Ahelium nuclei
   • Belectrons
   • Cneutrons
   • Delectromagnetic waves

   Show answer

   Explanation and discussion

5. Question 5· Elementary modern physics· WAEC

   Beta particles are

   • Ahelium nuclei
   • Bfast electrons
   • Celectromagnetic waves
   • Dneutrons

   Show answer

   Explanation and discussion

6. Question 6· Elementary modern physics· WAEC

   Which radiation is stopped by a sheet of paper?

   • Aalpha particles
   • Bbeta particles
   • Cgamma rays
   • DX-rays

   Show answer

   Explanation and discussion

7. Question 7· Elementary modern physics· WAEC

   The half-life of a radioactive substance is 2 days. What fraction of it remains after 6 days?

   • A1/3
   • B1/8
   • C1/6
   • D1/4

   Show answer

   Explanation and discussion

8. Question 8· Elementary modern physics· WAEC

   In the photoelectric effect, electrons are emitted only if the light's

   • Afrequency exceeds the threshold frequency
   • Bintensity is very high
   • Cwavelength is very long
   • Dcolour is red

   Show answer

   Explanation and discussion

9. Question 9· Elementary modern physics· WAEC

   The energy released in nuclear reactions comes from

   • Afriction
   • Bchemical bonds
   • Cthe mass defect, according to E = mc²
   • Delectric current

   Show answer

   Explanation and discussion

10. Question 10· Elementary modern physics· WAEC

    A radioactive substance has a half-life of 4 days. The fraction left after 12 days is

    • A1/16
    • B1/4
    • C1/3
    • D1/8

    Show answer

    Explanation and discussion

11. Question 11· Elementary modern physics· WAEC

    Light of photon energy 3.5 eV falls on a metal whose work function is 2.0 eV. Find the maximum kinetic energy of the emitted electrons.

    • A1.75 eV
    • B5.5 eV
    • C1.5 eV
    • D7.0 eV

    Show answer

    Explanation and discussion