Recent questions tagged ch5

The resistance of a wire is $5\: ohm \: at\: 50^{\circ}C$ and $6\: ohm \: at\: 100^{\circ}C$. The resistance of the wire at $0^{\circ}C$ will be

asked Feb 16, 2014 by thanvigandhi_1

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A battery is used to charge a parallel plate capacitor till the potential difference between the plates becomes equal to the electromotive force of the battery. The ratio of the energy stored in the capacitor and the work done by the battery will be

asked Feb 16, 2014 by thanvigandhi_1

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An electric bulb is rated $220V$- $100W$. The power consumed by it when it operates on $110V$ is

asked Feb 16, 2014 by thanvigandhi_1

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The resistance of a bulb filament is $ 100\Omega$ at a temperature of $100^{\circ}C$. If its temperature coefficient of resistance be $0.005 \: per^{\circ}C$ its resistance will become $200\Omega$ at a temperature of

asked Feb 15, 2014 by thanvigandhi_1

1 answer

In a Wheatstone's bridge their resistances P, Q and R connected in the three arms and the fourth arm is formed by the two resistances $S_1\: and \: S_2$ connected in parallel. The condition for bridge to be balanced will be

asked Feb 15, 2014 by thanvigandhi_1

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The Kirchhoff’s first law $ (\sum i = 0)$ and second law $(\sum iR = \sum E)$ where symbols have their usual meanings, are respectively based on conservation of

asked Feb 15, 2014 by thanvigandhi_1

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A material B has twice the specific resistance of A. A circular wire made of B has twice the diameter of a wire made of A. Then for the two wires to have the same resistance, the ratio $ \large\frac{l_A}{l_b}$ of their respective lengths must be

asked Feb 15, 2014 by thanvigandhi_1

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The resistance of hot tungsten filament is about 10 times the cold resistance. What will be the resistance of 100W and 200V lamp when not in use?

asked Feb 15, 2014 by thanvigandhi_1

1 answer

In a potentiometer experiment the balancing with a cell is at length 240 cm. On shunting the cell with a resistance of $ 2 \Omega$ the balancing length becomes 120 cm. The internal resistance of the cell is

asked Feb 15, 2014 by thanvigandhi_1

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An energy source will supply a constant current into the loads of its internal resistance is

asked Feb 15, 2014 by thanvigandhi_1

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A heater coil is cut into two equal parts and only one part is now used in the heater. The heat generated will now be

asked Feb 15, 2014 by thanvigandhi_1

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Two sources of equal emf are connected to an external resistance R. The internal resistance of the two sources are $R_1\: and \: R_2 (R_2 > R_1)$. If the potential difference across the source having internal resistance $R_2$ is zero then,

asked Feb 15, 2014 by thanvigandhi_1

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In the circuit the galvanometer $G$ shows zero deflection. If the batteries A and B have negligible internal resistance, the value of the resistor $R$ will be

asked Feb 15, 2014 by thanvigandhi_1

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Two voltameters one of copper and other of silver, are joined in parallel. When a total charge $q$ flows through a voltameters, equal amount of metals are deposited. If the electrochemical equivalents of copper and silver are $z_1\: and \: z_2$ respectively the charge which flows through the silver voltameter is

asked Feb 15, 2014 by thanvigandhi_1

1 answer

A moving coil galvanometer has 150 equal divisions. Its current sensitivity is 10 divisions per milliampere and voltage sensitivity is 2 divisions per millivolt. In order that each division reads 1 volt, the resistance in ohms needed to be connected in series with the coil will be

asked Feb 15, 2014 by thanvigandhi_1

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What is the dimensional formula for capacitance?

asked Feb 15, 2014 by thanvigandhi_1

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What is the dimensional formula for resistivity?

asked Feb 15, 2014 by thanvigandhi_1

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A 5V battery with internal resistance $2\Omega$ and a 2V battery with internal resistance $1\Omega$ are connected to a $ 10 \Omega $ resistor as shown in the figure. The current in the $ 10\Omega $ resistor is

asked Feb 15, 2014 by thanvigandhi_1

1 answer

Consider a block of conducting material of resistivity $ \rho$ shown in the figure. Current I enters at A and leaves from D. We apply superposition principle to find voltage $ \Delta V$ developed between B and C. The calculation is done in the following steps. \[\] (i) Take current I entering from A and assume it to spread over a hemispherical surface in the block. \[\] Calculate field E(r) at distance r from A by using ohm's law $E= \rho j$, where j is the current per unit area at r. \[\] (iii) From the r dependence of E(r) obtain the potential V(r) at r. \[\] (iv) Repeat (i), (ii) and (iii) for current I leaving D and superpose results for A and D \[\] For current entering at A, the electric field at a distance r from A is

asked Feb 14, 2014 by thanvigandhi_1

1 answer

Consider a block of conducting material of resistivity $ \rho$ shown in the figure. Current I enters at A and leaves from D. Apply the superposition principle and find the voltage $ \Delta V$ developed between B and C?

asked Feb 14, 2014 by thanvigandhi_1

1 answer

Shown in the figure below is a meter-bridge setup with null deflection in the galvanometer.The value of the unknown resistor $R$ is

asked Feb 14, 2014 by thanvigandhi_1

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Calculate the effective resistance between points A and B

asked Feb 14, 2014 by thanvigandhi_1

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What is the average drift speed of conduction electrons in a copper wire of cross-sectional area $1.0 \times 10^{–7}m^2$ carrying a current of $1.5 A$. Assume that each copper atom contributes roughly one conduction electron. The density of copper is $ 9.0 \times 10^3 kg/m^3 $ , and its atomic mass is $ 63.5 u.$

asked Feb 14, 2014 by thanvigandhi_1

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At what temperature would the temperature of a copper conductor be double its value at $0^{\circ}C\: \alpha_{Cu} = 4 \times 10^{-3}$

asked Feb 14, 2014 by thanvigandhi_1

1 answer