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Physics M.C.Q (1 Marks)

The Forces · Uttarakhand Board (UBSE) STD 12 Science (Uttarakhand - English Medium). 5 questions.

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M.C.Q (1 Marks)

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5 questions · 4 auto-graded MCQ + 1 self-marked written.

MCQ 11 Mark
When Neils Bohr shook hand with Werner Heisenberg, what kind of force they exerted?
  • A
    Gravitational.
  • ✓
    Electromagnetic.
  • C
    Nuclear.
  • D
    Weak.
Answer
Correct option: B.
Electromagnetic.
Explanation:

When Neils Bohr shook hand with Werner Heisenberg, electromagnetic force is exerted on each other. This is because when their hands made contact with each other, the atoms at the two surfaces come close to each other. The charged constituents of the atoms in the hands exert forces on each other and, as a result, a measurable force is produced.
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MCQ 21 Mark
The sum of all electromagnetic forces between different particles of a system of charged particles is zero:
  • A
    Only if all the particles are positively charged.
  • B
    Only if all the particles are negatively charged.
  • C
    Only if half the particles are positively charged and half are negatively charged.
  • ✓
    Irrespective of the signs of the charges.
Answer
Correct option: D.
Irrespective of the signs of the charges.
Explanation:

The sum of all electromagnetic forces between different particles of a system of charged particles is zero irrespective of the sign of the charges, because electromagnetic force is a vector quantity that depends upon the direction. So, we consider the directions while adding vector quantities.
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MCQ 31 Mark
Which of the following systems may be adequately described by classical physics?
  • A
    Motion of a cricket ball.
  • B
    Motion of a dust particle.
  • C
    A hydrogen atom.
  • D
    A neutron changing to a proton.
Answer
  1. Motion of a cricket ball.
  2. Motion of a dust particle.
Classical physics adequately describes the motion of a ball and the motion of dust particles. It also describes Newton's law of motion, Newton's law of gravitation, Laws of thermodynamics, Maxwell's electromagnetism and Lorentz force. Classical physics easily describes the system of heavenly bodies like the Sun, the Earth and the Moon. However, it is inadequate for describing systems of particles which have sizes much smaller than $10^{-6}m ($e.g., atom, nuclei and other elementary particles$)$.
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MCQ 41 Mark
Let E, G and N represent the magnitudes of electromagnetic gravitational and nuclear forces between two electrons at a given separation. Then:
  • A
    N > E > G
  • B
    E > N > G
  • C
    G > N > E
  • ✓
    E > G > N
Answer
Correct option: D.
E > G > N
Explanation:

Between two electrons at a given separation, the strongest acting force is the electromagnetic force. The gravitational force is the weakest force between any two particles. There is no nuclear force acting between them, because it exists only in the nucleus (between proton-proton or neutron-neutron or both).
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MCQ 51 Mark
A $60\ kg$ man pushes a $40\ kg$ man by a force of $60N$. The $40\ kg$ man has pushed the other man with a force of :
  • A
    $40N$
  • B
    $0N$
  • ✓
    $60N$
  • D
    $20N$
Answer
Correct option: C.
$60N$
According to Newton's third law, which states that an action$-$reaction pair of forces are equal in magnitude, the man who weighs $40\ kg$ will push the other man with the same force of $60N$.
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