Which of the following is incorrect?

A. Acceleration of a body is defined as the force acting on the body divided by the mass of the body

B. Lens maker formula: <img src="file:///C:/Users/devraj/AppData/Local/Temp/msohtmlclip1/01/clip_image002.png" style="height:25px; width:6px" /><span class="math-tex">\(\frac{1}{v} - {\rm{\;}}\frac{1}{u} = {\rm{\;}}\frac{1}{f}\)</span>

C. According to Kirchoff’s current law, at a node in an electric circuit, the sum of the currents entering equals the current leaving. 

D. Time period of a pendulum is: <span class="math-tex">\(2{\rm{\pi }}\sqrt {\frac{g}{l}}\)</span>

Please scroll down to see the correct answer and solution guide.

Right Answer is: D

SOLUTION

The second law of Newton’s law of motion gives relation between the mass, the acceleration and the acting force on the body, which says

F = ma, hence a = F/ m

The given lens maker formula is correct, where v is the image distance, u is the object distance and f is the focal length.

As per the KCl (current law), the sum of the current entering at a node in an electric circuit would be equal to the current leaving.

Time period of a pendulum is \(2{\rm{\pi }}\sqrt {\frac{l}{g}}\)