JAMB and WAEC Physics questions: Elementary modern physics

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

1. Question 1· Elementary modern physics· JAMB

   80 g of a radioactive substance decays to 10 g in 15 days. Find its half-life.

   • A7.5 days
   • B5 days
   • C3 days
   • D15 days

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2. Question 2· Elementary modern physics· WAEC

   Which radiation is stopped by a thin sheet of paper?

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

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3. Question 3· Elementary modern physics· JAMB

   A photon has energy 3.96 × 10⁻¹⁹ J. Find its frequency. [h = 6.6 × 10⁻³⁴ J s]

   • A2.6 × 10⁻⁵³ Hz
   • B6 × 10¹⁵ Hz
   • C6 × 10¹⁴ Hz
   • D1.7 × 10¹⁴ Hz

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4. Question 4· Elementary modern physics· JAMB

   Nuclear fission is the

   • Asplitting of a heavy nucleus into lighter nuclei
   • Bjoining of light nuclei
   • Cemission of light
   • Dloss of electrons

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5. Question 5· Elementary modern physics· JAMB

   Which radiation has the greatest penetrating power?

   • Agamma
   • Bbeta
   • Calpha
   • Dinfrared

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6. Question 6· Elementary modern physics· JAMB

   Light of photon energy 5 eV falls on a metal of work function 2 eV. Find the maximum kinetic energy of the emitted electrons.

   • A7 eV
   • B3 eV
   • C2.5 eV
   • D10 eV

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7. Question 7· Elementary modern physics· JAMB

   In a nuclear power station, energy is released mainly by

   • Aburning coal
   • Bfusion of hydrogen nuclei
   • Cfission of uranium nuclei
   • Dchemical reactions

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8. Question 8· Elementary modern physics· JAMB

   In the decay ²³⁸₉₂U → ²³⁴₉₀Th + X, the particle X is

   • Aa neutron
   • Ba beta particle
   • Ca gamma ray
   • Dan alpha particle

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9. Question 9· Elementary modern physics· JAMB

   How many neutrons are in the nucleus of ¹⁴₆C?

   • A6
   • B8
   • C14
   • D20

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10. Question 10· Elementary modern physics· JAMB

    A radioactive sample has a half-life of 4 days. The fraction remaining after 12 days is:

    • A1/2
    • B1/4
    • C1/3
    • D1/8

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11. Question 11· 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

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12. Question 12· Elementary modern physics· WAEC

    Which radiation is the most penetrating?

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

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13. Question 13· Elementary modern physics· WAEC

    Alpha particles are

    • Ahelium nuclei
    • Belectrons
    • Cneutrons
    • Delectromagnetic waves

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14. Question 14· Elementary modern physics· WAEC

    Beta particles are

    • Ahelium nuclei
    • Bfast electrons
    • Celectromagnetic waves
    • Dneutrons

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15. Question 15· Elementary modern physics· WAEC

    Which radiation is stopped by a sheet of paper?

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

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16. Question 16· 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

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17. Question 17· Elementary modern physics· JAMB

    When a nucleus emits a beta particle, its atomic number

    • Adecreases by 2
    • Bdecreases by 1
    • Cincreases by 1
    • Dstays the same

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18. Question 18· Elementary modern physics· JAMB

    Which radiation is the least penetrating?

    • AX-rays
    • Bbeta particles
    • Cgamma rays
    • Dalpha particles

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19. Question 19· Elementary modern physics· JAMB

    Find the energy of a photon of frequency 5 × 10¹⁴ Hz. (h = 6.6 × 10⁻³⁴ J s)

    • A1.32 × 10⁻⁴⁸ J
    • B3.3 × 10⁻¹⁹ J
    • C6.6 × 10⁻²⁰ J
    • D3.3 × 10⁻¹⁴ J

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20. Question 20· 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

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