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21 April 2014

Trend Setter Chapter Electricity numerical Problems for class 10 CBSE






1. How much work is done in moving a charge of 2 C across two points having a potentialdifference of 12 V?

2. A wire of resistance R is cut into five equal pieces. These five pieces of wire are then connected in parallel. If the resultant resistance of this combination be R then the ratio of resultant to the original will be?

3. A radio set draws a current of 0.36 A for 15 minutes. Calculate the amount of electriccharge that flows through the circuit.

4. Potential difference between two points of a wire carrying 2 ampere current is 0.1 volt.Calculate the resistance between these points.

5. A simple electric circuit has a 24 V battery and a resistor of 60 ohms. What will be the current in the circuit? The resistance of the connecting wires is negligible.

6.Find resistance between A and B in following network
Picture

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13 April 2014

CBSE Physics Numerical based on chapter - Electricity & its effects For (Class X)


NUMERICAL - Electricity and its effects For (Class X)

1. A resistance of 6 ohms is connected in series with another resistance of 4 ohms. A potential difference of 20 volts is applied across the combination. Calculate the current through the circuit and potential difference across the 6 ohm  resistance.
2. Calculate the number of electrons constituting one coulomb of charge per second through any cross section of a conductor.
3. How much work is done in moving a charge of 2 C across two points having a potential difference of 12 V ?
4. How much energy is given to each coulomb of charge passing through a 6 V battery ?
5. Calculate the work done in moving a charge of 5 Coulombs from a point at a potential of 210 Volts to another point at 240 Volts.
7. When a particle of charge 10 µC is brought from infinity to a point P, 2.0 mJ work is done by the external forces. What is the potential at P ?
9. How many electrons pass through a lamp in one minute if the current be 200 mA?
10. Calculate the current supplied by a cell if the amount of charge passing through the cell in 4 seconds is 12 C ?
11. A 2 Volt cell is connected to a 1 Ω resistor. How many electrons come out of the negative terminal of the cell in 2 minutes?
12. a)  How much current will an electric bulb draw from a 220 V source, if the resistance of the bulb filament is 1200 Ω ?
b)  How much current will an electric heater coil draw from a 220 V source, if the resistance of the heater coil is 100 Ω ?
13. The potential difference between the terminals of an electric heater is 60 Volts when it draws a current of 4 Ampere from a source. What current will the heater draw if the potential difference is increased to 120 Volt.  
14. A torch bulb when cold has 1Ω resistance. It draws a current of 0.3 Ampere when glowing from a source of 3 V. Calculate the resistance of the bulb when glowing and explain the reason for the difference in resistance.   

X Magnetic effects of currents [Conceptual Question with solution)

Question:
Imagine that you are sitting in a chamber with your back to one wall. An electron beam, moving horizontally from back wall towards the front wall, is deflected by a strong magnetic field to your right side. What is the direction of magnetic field?
Solution:
Here , An electron beam, moving horizontally from back wall towards the front wall so, the direction of current will be in the opposite direction i.e. horizontally from front wall towards the back wall or towards us. The direction of the deflection of [EMF] is towards our right.
Let us use left hand Flemings rule: Adjust center finger point towards us (I) and thumb towards right side (EMF) then our forefinger will point in downward direction (MF)
Question:
A current through a horizontal power line flows in east to west direction. What is the direction of magnetic field at a point directly below it and at a point directly above it?
Solution
The current is in the east-west direction. Applying the right-hand thumb rule, we get that the direction of magnetic field at a point below the wire is from north to south. The direction of magnetic field at a point directly above the wire is from south to north
Question:
Consider a circular loop of wire lying in the plane of the table. Let the current pass through the loop clockwise. Apply the right-hand rule to find out the direction of the magnetic field inside and outside the loop.
Solution
In the following diagram the current is flowing clockwise. If we are applying right hand thumb rule to the left side of the loop then the direction of magnetic field lines inside the loop are going into the table while outside the loop they are coming out of the table. If we are applying right hand thumb rule to the right side of the loop then the direction of magnetic field lines inside the loop are again going into the table while outside the loop they are coming out of the table.
Question:
A positively-charged particle (alpha-particle) projected towards west is deflected towards north by a magnetic field. The direction of magnetic field is (a) towards south (b) towards east (c) downward (d) upward
Solution:
(d) Upward
Here, the positively-charged particle (alpha-particle) projected towards west, so the direction of current is towards west. The deflection is towards the north.


Let us use left hand Flemings rule: Adjust center finger towards west (I) and thumb towards north (EMF) then our forefinger will point in upward direction (MF)