Podcast
Questions and Answers
What is Kirchhoff's second law based on?
What is Kirchhoff's second law based on?
- Conservation of energy (correct)
- Conservation of mass
- Conservation of charge
- Conservation of momentum
To minimize the error due to contact resistance in a meter bridge, what should be done?
To minimize the error due to contact resistance in a meter bridge, what should be done?
- Using uniform wire
- Connecting both resistances only in one gap
- Interchanging the position of known and unknown resistances (correct)
- Obtaining the null point near the ends of the wire
What is the SI unit of potential gradient?
What is the SI unit of potential gradient?
- V-m
- V/cm
- V-cm
- V/m (correct)
Which instrument can measure terminal potential difference as well as electromotive force?
Which instrument can measure terminal potential difference as well as electromotive force?
When the null point is obtained in a potentiometer, where is the current drawn from?
When the null point is obtained in a potentiometer, where is the current drawn from?
If the potential gradient of a wire decreases, what happens to its length?
If the potential gradient of a wire decreases, what happens to its length?
What is the percentage error in the voltmeter reading when it balances at 350 cm with a reading of 1.8V, given that the standard cell's emf is 1.5V and was balanced at 300 cm?
What is the percentage error in the voltmeter reading when it balances at 350 cm with a reading of 1.8V, given that the standard cell's emf is 1.5V and was balanced at 300 cm?
How would you determine the internal resistance of a cell using a potentiometer?
How would you determine the internal resistance of a cell using a potentiometer?
Why is a potentiometer preferred over a voltmeter for measuring emf?
Why is a potentiometer preferred over a voltmeter for measuring emf?
In the right hand rule, what is the direction of magnetic induction if the current flows in an anticlockwise direction?
In the right hand rule, what is the direction of magnetic induction if the current flows in an anticlockwise direction?
For a conductor with two straight segments of length L and a semicircular segment with radius R carrying a current I, what is the magnetic field at point P?
For a conductor with two straight segments of length L and a semicircular segment with radius R carrying a current I, what is the magnetic field at point P?
What happens to a stationary electron when exposed to a strong magnetic field?
What happens to a stationary electron when exposed to a strong magnetic field?
What is the resistance needed to be connected in series with a galvanometer to convert it into a voltmeter of range 4Vm?
What is the resistance needed to be connected in series with a galvanometer to convert it into a voltmeter of range 4Vm?
In a meter bridge experiment, what happens if the balance point is found at 30 cm from the end A when the resistor R is 15 Ω (right gap)?
In a meter bridge experiment, what happens if the balance point is found at 30 cm from the end A when the resistor R is 15 Ω (right gap)?
How can errors in a meter bridge experiment be minimized?
How can errors in a meter bridge experiment be minimized?
What should be the resistance introduced in the resistance box to achieve a potential drop of one microvolt per cm in a potentiometer wire?
What should be the resistance introduced in the resistance box to achieve a potential drop of one microvolt per cm in a potentiometer wire?
When comparing the emf's of two cells using a potentiometer by connecting them individually, what does the balance point indicate?
When comparing the emf's of two cells using a potentiometer by connecting them individually, what does the balance point indicate?
If a cell with an e.m.f of 2V and internal resistance of 0.5Ω is connected in series with another cell, what would be the effect on overall voltage and internal resistance?
If a cell with an e.m.f of 2V and internal resistance of 0.5Ω is connected in series with another cell, what would be the effect on overall voltage and internal resistance?
Study Notes
Resistance and Meter Bridge
- To balance a network, a 9 Ω resistance is connected across the 18 Ω resistance.
- A galvanometer of resistance G can measure a maximum safe voltage of Vm.
- To convert a galvanometer into a voltmeter of range nVm, a resistance of (n-1) G should be connected in series.
Meter Bridge Experiment
- A meter bridge is used to determine unknown resistances.
- A neat circuit diagram is required to explain the process.
- Errors in the meter bridge experiment can occur due to:
- Contact resistance
- Gap resistance
- These errors can be minimized by:
- Interchanging the position of known and unknown resistances
- Using a uniform wire
Potential Gradient
- Potential gradient is measured in V/m.
- It is measured using a potentiometer.
- A potentiometer is used to compare the emf's of two cells by connecting the cells individually.
Potentiometer
- A potentiometer is used to measure the emf of a cell.
- It can be used to compare the emf's of two cells by connecting the cells individually or by the combination method.
- The internal resistance of a cell can be determined using a potentiometer.
- The formula for internal resistance can be derived using a potentiometer.
Magnetic Effect of Electric Current
- According to the right-hand rule, the direction of magnetic induction is perpendicular and outwards if the current is directed in an anticlockwise direction.
- The magnetic field B at point P can be calculated using the formula B = (μ₀ * I) / (4 * π * R).
Capacitance and Electric Potential
- The capacitance of a parallel plate capacitor with a dielectric slab between the plates can be calculated using the formula C = (ε₀ * εr * A) / d.
- The electric potential due to an electric dipole can be derived using the formula V = (p * cosθ) / (4 * π * ε₀ * r²).
Current Electricity
- Kirchhoff's second law (voltage law) is based on the conservation of energy.
- The error due to contact resistance in the meter bridge experiment can be minimized by interchanging the position of known and unknown resistances.
- The SI unit of potential gradient is V/m.
- A potentiometer can measure terminal potential difference as well as electromotive force (emf).
- When null point is obtained in the potentiometer, the current is drawn from the main battery.
- If the potential gradient of a wire decreases, its length increases.
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Description
Test your knowledge on balancing resistors network and using a meter bridge to determine unknown resistances. Questions include finding the resistance to balance a network and calculating the resistance needed to convert a galvanometer into a voltmeter of specific range.
