Question

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.

Assertion A: An electron microscope can achieve better resolving power than an optical microscope.

Reason R: The de Broglie’s wavelength of the electrons emitted from an electron gun is much less than the wavelength of visible light.

In light of the above statements, choose the correct answer from the options given below:

• A. A is true but R is false.
• B. Both A and R are true but R is NOT the correct explanation of A.
• C. Both A and R are true and R is the correct explanation of A.
• D. A is false but R is true.

Answer 1

The correct option is C

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

Explanation for Assertion statement:

We know that,

1. Resolving power is inversely proportional to the wavelength of the wave used in the microscope such as.
2. The resolving power of an electron microscope is higher than that of an optical microscope.

Hence, an electron microscope can achieve better resolving power than an optical microscope.

Explanation for Reason statement:

As we know,

1. The de Broglie’s wavelength of the electrons is, $\lambda =\frac{h}{mv}$ where $h$ is Planck constant and $m$ is the mass of the electron and $v$ is the velocity of the electron.
2. As of the high resolving power of an electron microscope, according to de Broglie’s equation, the wavelength of an electron is much less than visible light.

Hence, option C is correct