The waves used in radar are MCQ with Answer and Explanation
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Question #1
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Assertion (A): A fuse wire must have a high resistance and a low melting point. Reason (R): This ensures it melts quickly and breaks the circuit when an excessively high current flows.
Correct Answer: Option C
Explanation:
A fuse is a safety device. It must have a relatively high resistance so that it produces heat quickly when a large current passes through (H = I²Rt). It must have a low melting point so that this heat causes it to melt immediately, breaking the circuit and protecting appliances. Thus, both A and R are true, and R explains A.
A fuse is a safety device. It must have a relatively high resistance so that it produces heat quickly when a large current passes through (H = I²Rt). It must have a low melting point so that this heat causes it to melt immediately, breaking the circuit and protecting appliances. Thus, both A and R are true, and R explains A.
Question #2
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Beta rays emitted by radioactive substances are essentially:
Correct Answer: Option B
Explanation:
During beta decay, a neutron in an unstable nucleus transforms into a proton and an electron. The proton remains in the nucleus, but the electron is ejected at high speed. These ejected, high-energy electrons are called beta rays (or beta particles). Gamma rays are electromagnetic waves, and alpha particles are helium nuclei.
During beta decay, a neutron in an unstable nucleus transforms into a proton and an electron. The proton remains in the nucleus, but the electron is ejected at high speed. These ejected, high-energy electrons are called beta rays (or beta particles). Gamma rays are electromagnetic waves, and alpha particles are helium nuclei.
Question #3
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An element X has atomic number 17 and mass number 35. Number of neutrons is
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