Advertisements
Advertisements
प्रश्न
Two electric bulbs rated 100 W; 220 V and 60 W; 220 V are connected in parallel to electric mains of 220 V. Find the current drawn by the bulbs from the mains.
उत्तर
Firstly calculating the resistance of the electric bulbs,
P=`"V"^2/"R"`
⇒ `"R"="V"^2/"P"`
⇒ `"R"_1 =220^2/100 =484 Ω`
⇒ `"R"_2=220^2/60=2420/3 Ω`
`"R"_"eq" = ("R"_1"R"_2)/("R"_1+"R"_2)=(484xx(2420//3))/(484+(2420//3))=302.5Ω`
Total current drawn by the bulbs from the mains supply,
`"I"=220/302.5=0.73 "A"`
APPEARS IN
संबंधित प्रश्न
Which of the following units could be used to measure electric charge?
(a) ampere
(b) joule
(c) volt
(d) coulomb
Which instrument is used to measure electric current? How should it be connected in a circuit?
Ten bulbs are connected in a series circuit to a power supply line. Ten identical bulbs are connected in a parallel circuit to an identical power supply line.
(b) In which circuit, if one bulbs be brighter?
Draw a circuit diagram showing two lamps, one cell and a switch connected in series.
How can you change the brightness of the lamp?
Match the pairs.
| ‘A’ Group | ‘B’ Group |
| 1. Free electrons | a. V/R |
| 2. Current | b. Increases the resistance in the circuit |
| 3. Resistivity | c. Weakly attached |
| 4. Resistances in series | d. VA/LI |
Complete the following sentence:
A fuse is connected in ........... with the ......... wire.
If a fuse contains a 5 A fuse wire and the voltage is 240 V, what is the maximum power (wattage) which may be taken from the circuit?
An auto lamp is joined to a battery of e.m.f. 4 V and internal resistance 2.5Ω. A steady current of 0.5 A flows through the circuit. Calculate the
(a) Total energy provided by battery in 10 minutes,
(b) Heat dissipated in the bulb in 10 minutes.
Fig . shows the core of a transformer and i ts input and output connections
State the material used for the core and describe th e structure of the core.
(a) Use the values given in the diagram to calculate the turns ratio for the transformer and connections, labeling all parts of the diagram .
(b) If a current of 2 A is taken from th e output, calculate th e current in the input circuit (Assume the transformer to be ideal ).
What determines the direction of flow of electrons between two charged conductors kept in contact?
