The potential difference \( V \) across the filament of the bulb shown in the given Wheatstone bridge varies as \( V = i(2i + 1) \), where \( i \) is the current in ampere through the filament of the bulb. The emf of the battery (\( V_a \)) so that the bridge becomes balanced is:
According to Fajan's rules, which of the following is not correct about covalent character?
Calculate the determinant of the matrix:
Evaluate the integral: \[ \int \frac{\sec x}{3(\sec x + \tan x) + 2} \,dx \]
When the object and the screen are 90 cm apart, it is observed that a clear image is formed on the screen when a convex lens is placed at two positions separated by 30 cm between the object and the screen. The focal length of the lens is: