A voltmeter having a resistance of $ 998 O $ is connected to a cell of emf 2 V and internal resistance $ 2 O $ . The error in the measurement of emf will be
- $ 4 \times 10^{-1} V $
- $ 2 \times 10^{-3} V $
- $ 4 \times 10^{-3} V $
- $ 2 \times 10^{-1} V $
The Correct Option is C
Approach Solution - 1
$ i = \frac{E}{R + r} $
Given, $ \, \, \, E = 2V, R = 998 O $ and $ r = 2O $
$ \therefore \, \, \, i = \frac{2}{998 + 2} = \frac{1}{500} A $
Error in value of emf
= Actual value of emf - measured emf
Emf V = E - ir
$ \, \, \, \, = 2 \times \frac{1}{500} \times 2 = 2 - \frac{1}{250} $
$ \therefore Error = 2 - \bigg( 2 - \frac{1}{250} \bigg ) = \frac{1}{250} $
$ = 4 \times 10^{-3} V $
Approach Solution -2
Ans. Inside the magnetic field, induced electromotive force and current occur, and the current is produced by varying the magnetic field. Induced electromotive force and current are related to Faraday's law of electromagnetic induction. When magnetic flux is conducted through a coil, a voltage known as the induced electromagnetic force is produced. When a wave of current begins to flow in the wire, an electrical effect is produced on the coil's opposite side.
The magnetic field may be changed to generate current in the coil. The current moves because of changes in the magnetic field. An induced electromotive force is produced when the magnetic flux modifies as it travels around a loop. Generators, galvanometers, and transformers all employ induced electromotive force.
When change in the magnetic field of an electrochemical cell produces electric potential, it is known as electromotive force or EMF. Electromotive force is work done on a unit electric charge because, in order to convert energy from one form to another, a battery or generator is used where one terminal is negatively charged whereas the other one is positively charged.
Electromotive force is used in electromagnetic flow meters.
Electromotive force is expressed as:
(ε) = v + lr
Where,
v = voltage
l = current
r = internal resistance
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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.