physics

If the fraction of the atoms of a radioactive material left after 120years is 1/64. What is the half-life of the material?

A. 24 years B. 20 years C. 10 years D. 2 years Correct Answer: Option B - 20 years Explanation…

4 years ago

An electric generator with a power output of 3.0KW at a voltage of 1.5KV distributes power along cables of resistance 20.0Ω. The power loss in the cables is?

A. 80.0W B. 40.0W C. 10.0W D. 0.1W Correct Answer: Option A = 80.0W Explanation Power input = 3KW =…

4 years ago

A gas would serve as an electrical conductor under?

A. reduced pressure and high current B. increased magnetic field C. reduced pressure and reduced potential D. exposure to visible…

4 years ago

In a pure semiconductor; the number of electrons in the conduction band is?

A. less than the number of holes in the valence band B. equal to the number of holes in the…

4 years ago

What optical instrument can best be constructed with converging lenses of focal lengths 50cm and 5cm?

A. Compound microscope B. Galileo's telescope C. Terrestrial telescope D. Astronomical telescope Correct Answer: Option D - Astronomical telescope

4 years ago

A cell of internal resistance 0.01Ω can be measured accurately using the?

A. Ohm meter B. metre bridge C. potentiometer D. electroscope Correct Answer: Option C - potentiometer

4 years ago

A projection lantern is used to give the image of a slide on a screen. If the image is 24 times as large as the slide and the screen is 72.0m from the projecting lens, what is the position of the slide from the lens?

A. 0.3m B. 3.0m C. 3.5m D. 4.0m Correct Answer: Option B - 3.0m Explanation V = 72m U =…

4 years ago

If a charged ion goes through combined electric and magnetic fields; the resultant emergent velocity of the ion is?

A. E/B B. EB C. B/E D. E - B Correct Answer: Option A = E/B

4 years ago

A radio is operated by eight cells each of e.m.f. 2.0V connected in series. If two of the cells are wrongly connected, the net e.m.f. of the radio is?

A. 8V B. 10V C. 12V D. 16V Correct Answer: Option C = 12V Explanation Net e.m.f = (8 x…

4 years ago

The main reason for making the cover of a vacuum flask airtight is to prevent heat loss by?

A. convection B. conduction C. radiation D. evaporation Correct Answer: Option A - convection

4 years ago
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