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What is potentiometer ? Explain principle of potentiometer. |
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Answer» Solution :`rArr` Potentiometer is a device in which continously varying POTENTIAL difference can be obtained and measured also. `rArr` Device measuring potential difference is called potentiometer. Principle:  `rArr` As shown in figure, a BATTERY having emf t and INTERNAL resistance r is connected with resistance box R and wire with uniform cross- section and uniform resistance per unit length (AB) are connected in series. `rArr`Resistance box (R) is always not needed. `rArr` length of AB wire = L `rArr` Let resistance of wire per unit length is `rho` . `therefore ` Resistance of wire AB = L `rho` `rArr` Let value of resistance obtained (used) from resistance box is R. `thereforre ` Current flowing in the wire, `I = (epsilon)/(R + L rho + r)"" `.... (1) `rArr ` If length of AC wire is l then, resistance of AC wire = `rho ` l `rArr` Potential difference between A and C = current`xx ` (resistance of AC ) `therefore V_(l) = epsilon (l) = I rho l ""`....(2) `rArr thereforeepsilon (l) = ((epsilon rho )/(L rho + R + r)) . l ` `therefore epsilon (l) = V = phi `l Where `phi ` or `sigma ` of K is called potential gradient. `rArr` Principle : Potential difference between two point of wire is directly proportional to distance between two points. `rArr` Its unit is `Vm^(-1) ` and dimensional formula `[M^(1) L^(1) T^(-3) A^(-1) ] ` |
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