Download ElectricalMaintenance 1 Unit1 QuestionBank

STD XI
QUESTION BANK (UNIT TEST 1)
ELECTRICAL MAINTENANCE – PAPER 1
CHAPTER 1: ELECTRICAL SYMBOLS
Draw the symbols of the following:
1.
2.
3.
4.
5.
6.
7.
General Symbols
Switches and Fuses
Meters
Socket Outlets
Main and Distribution fuse board
Appliances
Motors and Generators
CHAPTER 2: ELECTRIC CIRCUIT
1. Define the following terms with units:
a. Electric current
b. Resistance
c. Conductance
d. Electromotive Force (emf)
e. Potential Difference (P.d.)
f. Voltage
g. Specific Resistance
2. What is an electrical circuit? Explain the essential parts of an electrical
circuit along with their functions.
3. What do you mean by open, closed and short circuit?
4. State and explain ohms law.
5. State the laws of resistance.
OR
On what factors does the resistance of a substance depend?
6. State the practical cases of series and parallel connection.
NUMERICALS
1. The resistance of a 220V incandescent lamp is 250Ω. Calculate the current
taken by the lamp.(Ans. 0.88A)
2. Resistance of the motor is 220Ω and maximum current that it can take is
2A. Find the main supply voltage on which it works effectively. (Ans. 440V)
3. A platinum wire 40m long, 0.04cm in diameter has a resistance of 35Ω. Find
the specific resistance of the material. (Ans. 11µΩ-cm)
4. Determine the resistance of a conductor having 1mm2 cross sectional area
and 15m long. The specific resistance of the conductor material is 1.75 x 108
Ω-m. (Ans. 0.2625Ω)
5. Three resistances of 10Ω, 20Ω and 40Ω are connected in (a) series (b)
parallel. Find in each case the following: (i) total resistance (ii) total current
(iii) voltage across each resistance (iv) current through each resistance
when the supply voltage is 230V.
{Ans. Series: (i)total resistance=70Ω, (ii)total current=3.29A, (iii)Voltage
across each resistance (10Ω)=32.9V, (20Ω)=65.8V, (40Ω)=131.42V (iv)
Current in each resistance is same as 3.29A
Parallel: (i)total resistance=5.71Ω, (ii)total current=40.28A, (iii) Voltage
across each resistance is same as 230V (iv)Current through each resistance
(10Ω)=23A, (20Ω)=11.5A, (40Ω)=5.75A }
6. Find the total resistance and total current of the following: (Ans. Total
resistance=8Ω, total current=25A)
7. Solve the circuit and find out: (i) total resistance (ii) total current. (Ans.
Total resistance=30Ω, total current=8A)
8. Calculate effective resistance of the following combination of resistance
when p.d. of 60V is applied between A and B. Also calculate total current in
the circuit. (Ans. Effective resistance=10Ω, total current=6A)
9. Find the supply voltage if the current in 10Ω resistance is 10A (Ans. 200V)
10.A resistance of 10Ω is connected to two batteries as shown in the figure.
Find the current in the resistance and its direction. (Ans. Current=0.45A,
Current will flow from A to B)