Q.1
Two electric bulbs have tungsten filament of same length. If one of them gives 60watts and other 100watts, then
  • a) 100 watt bulb has thicker filament
  • b) 60 watt have thicker filament
  • c)both filaments are of same thickness
  • d)the thickness of filaments can not be compared
Q.2
A house served by a 220V supply line. In a circuit protected by a fuse marked 9A , the maximum number of 60W lamps in parallel that can be turned on is
  • a) 44
  • b) 22
  • c) 20
  • d) 33
Q.3
A tap supply water at 22°C. A man takes 1 litre of water per minute at 37°C from the geyser. The power of geyser is
  • a)2100 W
  • b) 525W
  • c)1050W
  • d)1575W
Q.4
A uniform wire when connected directly across a 200V line produces heat H per sec. If the wire is divided into n parts and all parts are connected in parallel across a 200V line, the heat produced per second will be
  • a) H
  • b) nH
  • c)n2H
  • d)H/n²
Q.5
Two electric bulbs first of 2200volts, 100 watt and the second of 220 volt, 25 watt are connected in series across a 220 volt line. then the electric currents in the first and second bulb are respectively
  • a) (1/11) amp and (1/11) amp
  • b) (20/44) amp and (5/44) amp
  • c)(25/88) amp and (25/88) amp
  • d)(1/22) amp and (1/22) amp
Q.6
A cell send a current through a resistance R1 for time t, next the same cell sends current through another resistance R2 for the same time t. If the same amount of heat is developed in both the resistance, then the internal resistance of the cell is
  • c) √(R1 R2)
  • a) (R₁ + R₂) /2
  • b) (R₁ - R₂) /2
  • d) √(R₁ R₂) / 2
Q.7
The two head lamps of a car are in parallel. They to gather consume 48 watt with the help of a 6 volt battery. The resistance of each bulb is
  • a) 0.67 ohms
  • b) 3.0 ohms
  • c)4.0 ohms
  • d)1.5 ohms
Q.8
A 200 watt and 100 watt bulbs, both meant for operation at 220 volt, are connected in series, When connected to a 220 volt supply, the power consumed by them will be
  • a) 33 watt
  • b) 66 watt
  • c)100 watt
  • d)300 watt
Q.9
TWo identical heaters, each marked 1000 watt, 250 volt are placed in parallel with each other and connected to a 250 volt supply. Their combination rate of heat will be
  • a) 250 W
  • b) 500 W
  • c) 1000 W
  • d) 2000 W
Q.10
An immersion heater is rated 830 watt, 220 volt. It is used on 220 volt line to heat 1 litre of water from 20°C to 30°C. Then the time taken is about
  • a)100 sec
  • b) 50 sec
  • c)836 sec
  • d)418 sec
Q.11
Electric bulbs rated 50 watt and 100 volt and glowing at full power, are used in parallel with a battery of emf, 120Volts and internal resistance 10 ohm. The maximum number of bulbs that can be connected in the circuit when glowing at full power is
  • a) 8
  • b) 6
  • c)4
  • d)2
Q.12
Two resistors having equal resistances are joined in series and current is passed through the combination. Neglect any variation in resistance as the temperature changes in a given time interval: [ MPPMT 1999]
  • a) Equal amount of thermal energy must be produced in the resistors
  • b) Unequal amount of thermal energy may be produced
  • c)The temperature must rise equally in the resistors
  • d)The temperature must rise unequally in the resistors
Q.13
You are given resistance wire of length 50cm and a battery of legible resistance. In which case the maximum amount of heat is generated
  • a)when the wire is connected across the battery directly
  • b) when the wire is divided into two parts and both the parts are connected across the battery in parallel
  • c)when the wire is divided into four parts and all the four parts are connected across the battery in parallel
  • d)when only half the wire is connected across the battery
Q.14
Resistance R1 and R2 are joined in parallel and a current is passed so that the amount of heat liberated in H1 and H2 respectively. The ratio H1 / H2 has the value: [ MPPMT 1994]
  • c)R12 / R22
  • d)R22 / R12
  • a) R₂ / R₁
  • b) R₁ / R₂
Q.15
TWo bulbs of 500W and 300W are manufactured to operate on 220 V line. If their resistance are R1 and R2 respectively, the value of R1 and R2 is
  • a) 5/3
  • b) 3/5
  • c)25/9
  • d)9/25
Q.16
An electric kettle work at 220 volt and 4 A current. To boil 1kg water at room temperature 20°C it will take time [ Boiling point of water 100°C]
  • a) 6.0 minutes
  • b) 6.3 minutes
  • c) 12.6 minutes
  • d) 12.8 minutes
Q.17
Ten identical electric bulbs,each rated 220 volt, 50 watt are used in parallel on 220 line for 10 hours per day in a month of 30 days. Then the electrical energy consumed in kilowatt hours is [ CPMT 19991]
  • a)1500
  • b) 15000
  • c)15
  • d)150
Q.18
Element in electric stove is made of
  • a) copper
  • b) nichrome
  • c)platinum
  • d)tungsten
Q.19
The resistance of an electric bulb, marked 220V, 100W is [ MPPMT 1997]
  • a)2.2 Ω
  • b) 5/11 Ω
  • c)500/11 Ω
  • d)484 Ω
Q.20
If the current in an electric bulb decreases by 0.5 %, then the power in the bulb decreases by approximately
  • a) 0.5 %
  • b) 1.0 %
  • c) 2.0 %
  • d) 0.25 %
Q.21
The power rating of an electric motor which draws a current of 3.75 amp when operated at200volts is about
  • a)1 H.P.
  • b) 500 watts
  • c)54 watts
  • d)750 H.P.
Q.22
A resistance R1 dissipates the power P when connected to a certain generator, if a resistance R2 is put in series with R1, the power dissipated by R1 : [ CPMT 1985]
  • a) decreases
  • b) increases
  • c)remains the same
  • d)any one of the above depending upon the relative value of R1 and R2
Q.23
The fuse wire is made of
  • a) copper
  • b) tungsten
  • c)lead-tin alloy
  • d)nichrome
Q.24
Two cities are 150 km apart. Electric power is sent from one city to another city through copper wires. The fall of potential per kilometer is 8 volt and the average resistance per kilometer is 0.5 Ω. The power loss in the wires is
  • a) 19.2 watt
  • b) 19.2 kilowatt
  • c) 19.2 joule
  • d) 19.2 kWh
Q.25
A combination of two resistance of 2Ω and 2/3 Ω connected in parallel is joined across a battery of emf of 3 volt and of negligible internal resistance. The energy given out per sec will be
  • a) (1/2) × 3 2 joules
  • b) (1/2)2 × 3 2 joules
  • c) 2 × 3 joules
  • d) 32 × 2 joules
Q.26
In the circuit shown , the heat produced in the 5Ω resistor due to current flowing it, is 10 calories per second. Then the heat generated in the 4 Ω resistor is
ch-15_que_no-113_img_no1.png
  • a)1 calories per second
  • b) 8 calories per sec
  • c)3 calories per second
  • d)4 calories per sec
Q.27
The resistance of coil of a small motor of 10 watt, 20V is 12Ω. The rate of heat produced in the motor is
  • a) 3 W
  • b) 7 W
  • c)10 W
  • d)33.3 W
Q.28
Electric room radiator which operates at 225 volts has resistance of 50 Ω. Power of the radiator is approximately:
  • a) 100 watt
  • b) 450 Watt
  • c)750 watt
  • d)1000 watt
Q.29
How much electric energy is consumed in using a 100 W lamp for 6 hours every day for 30 days?
  • a) 0.5 kJ
  • b) 0.5 kWh
  • c) 18 kJ
  • d) 18 kWh
Q.30
A lamp is marked 60W, 220V. If it operates at 200V, the rate of consumption of energy will
  • a)increase
  • b) decrease
  • c)remain unchanged
  • d)cant say it may increase or decrease
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