State the underlying principle of a potentiometer. Write two factors by which current sensitivity of a potentiometer can be increased. Why is a potentiometer preferred over a voltmeter for measuring the emf of a cell?
CBSE OUTSIDE DELHI - SET 2 PATNA 2015
Download our app for free and get startedPlay store
Principle: The potential drop, across a part of a length l of a uniform wire of length L (L>l), is proportional to the length l.
Two factors:
  1. Increasing the length L of the wire.
  2. Connecting a suitable resistance, R, in series with the potentiometer wire.
Reason: At the balance position, there is no net current drawn, from the cell and the cell is effectively in an open circuit condition. This is not so for a voltmeter.
art

Download our app
and get started for free

Experience the future of education. Simply download our apps or reach out to us for more information. Let's shape the future of learning together!No signup needed.*

Similar Questions

  • 1
    A resistor R and an inductor L are connected in series to a source $\text{V}=\text{V}_0\sin\omega\text{t}.$
    Find:
    1. Peak value of the voltage drops across R and across L,
    2. Phase difference between the applied voltage and current. Which of them is ahead?
    View Solution
  • 2
    1. In Young's double slit experiment, two slits are 1 mm apart, and the screen is placed 1 m away from the slits. Calculate the fringe width when light of wavelength 500 nm is used.
    2. What should be the width of each slit in order to obtain 10 maxima of the double slits pattern within the central maximum of the single slit pattern?
    View Solution
  • 3
    1. Find the value of the phase difference between the current and the voltage in the series LCR circuit shown below. Which one leads in phase: current or voltage?
    2. Without making any other change, find the value of the additional capacitor $C_1,$ to be connected in parallel with the capacitor C, in order to make the power factor of the circuit unity.
    View Solution
  • 4
    1. Define the term ‘intensity of radiation’ in terms of photon picture of light.
    2. Two monochromatic beams, one red and the other blue, have the same intensity. In which case (i) The number of photons per unit area per second is larger, (ii) The maximum kinetic energy of the photoelectrons is more? Justify your answer.
    View Solution
  • 5
    1. Distinguish between a conductor and a semi conductor on the basis of energy band diagram.
    2. The following figure shows the input waveforms (A, B) and the output waveform (Y) of a gate. Identify the gate, write its truth table and draw its logic symbol.
    View Solution
  • 6
    Calculate the equivalent capacitance between points A and B in the circuit below. If a battery of 10 V is connected across A and B, calculate the charge drawn from the battery by the circuit.
    View Solution
  • 7
    Two identical cells of emf 1.5 V each joined in parallel supply energy to an external circuit consisting of two resistances of 7 $\Omega$ each joined in parallel. A very high resistance voltmeter reads the terminal voltage of cells to be 1.4 V. Calculate the internal resistance of each cell.
    View Solution
  • 8

    Figure shows a typical circuit for a low-pass filter. An AC input $V_{i }= 10mV$ is applied at the left end and the output $V_0$ is received at the right end. Find the output voltage for ν = 10kHz, 1.0MHz and 10.0MHz. Note that as the frequency is increased the output decreases and, hence, the name low-pass filter.
    View Solution
  • 9
    Figure shows a light bulb (B) and iron cored inductor connected to a dc battery through a switch (S).
    1. What will one observe when switch (S) is closed?
    2. How will the glow of the bulb change when the battery is replaced by an ac source of rms voltage equal to the voltage of dc battery? Justify your answer in each case.
    View Solution
  • 10
    1. Describe the working of photodiode by drawing the circuit diagram.
    2. Draw the characteristics of a photodiode for different illumination intensities.
    3. Why is photodiode operated in reverse bias even though the reverse bias current is much weaker than the current in forward bias?
    View Solution