In an experiment to find emf of a cell using potentiometer, the length of null point for a cell of emf $15 \,V$ is found to be $60 \,cm$ If this cell is replaced by another cell of emf $E$, the length-of null point increases by $40 \,cm$ The value of $E$ is $\frac{x}{10} V$ The value of $x$ is _______
Correct Answer: 25
Solution and Explanation
\[ \frac{E_1}{E_2} = \frac{l_1}{l_2} \] \[ \frac{1.5}{E_2} = \frac{60}{60 + 40} = \frac{6}{10} = \frac{3}{5} \] \[ E_2 = \frac{5}{2} = \frac{x}{10} \] \[ x = 25 \]
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Concepts Used:
Current Electricity
Current electricity is defined as the flow of electrons from one section of the circuit to another.
Types of Current Electricity
There are two types of current electricity as follows:
Direct Current
The current electricity whose direction remains the same is known as direct current. Direct current is defined by the constant flow of electrons from a region of high electron density to a region of low electron density. DC is used in many household appliances and applications that involve a battery.
Alternating Current
The current electricity that is bidirectional and keeps changing the direction of the charge flow is known as alternating current. The bi-directionality is caused by a sinusoidally varying current and voltage that reverses directions, creating a periodic back-and-forth motion for the current. The electrical outlets at our homes and industries are supplied with alternating current.