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Electric Charges and Fields — Physics STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 SciencePhysicsElectric Charges and Fields1 Mark
Question
For two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
  1. Both A and R are true, and R is the correct explanation of A.
  2. Both A and R are true, but R is not the correct explanation of A.
  3. A is true but R is false.
  4. A is false and R is also false.
Assertion (A): Electric force acting on a proton and an electron, moving in a uniform electric field is the same, where as acceleration of electron is 1836 times that of a proton.
Reason (R): Electron is lighter than proton.
✓

Answer

  1. Both A and R are true, and R is the correct explanation of A.

Explanation:

As F = qE, and charge (q) on an electron and on a proton has the same magnitude, therefore force (F) on each is same. Now, acceleration $\text{a}=\frac{\text{F}}{\text{m}}.$

Mass of electron $=\frac{1}{1836}$ mass of a proton. Therefore, acceleration of electron is 1836 times that of a proton.

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