Beta rays emitted by radioactive substances are essentially:
A. Electromagnetic waves
B. High-speed electrons
C. Neutrons
D. Helium nuclei
Answer: Option B
Solution (By JKSSB Mock Tests)
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.
Explanation:
Gamma rays have wavelengths < 10⁻¹² m, shortest in EM spectrum. X-rays 10⁻¹⁰-10⁻⁸ m. UV 10⁻⁸-4×10⁻⁷ m. IR longer. So gamma rays shortest. Highest frequency, energy.
Explanation:
Kepler's Second Law states that the line joining a planet to the Sun sweeps out equal areas in equal intervals of time (areal velocity is constant). Because the gravitational force is a central force (acting strictly along the radius vector), it exerts zero torque on the planet. When net torque is zero, angular momentum is strictly conserved.
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