Advertisements
Advertisements
प्रश्न
An electric heater which is connected to a 220 V supply line has two resistance coils A and B of 24 Ω resistance each. These coils can be used separately (one at a time), in series or in parallel. Calculate the current drawn when:
(a) only one coil A is used.
(b) coils A and B are used in series.
(c) coils A and B are uses in parallel.
Advertisements
उत्तर
(a) When only one coil, A is used:
V = IR
220 = 24 I
I = 9.2 A
(b) When coils, A and B are used in series:
Total resistance R = RA+ RB = 48 Ω
V = IR
220 = 48 I
I = 4.58 A
(c) When coils, A and B are used in parallel:
1/R = 1/RA+ 1/RB
Here, RA = 24 Ω and RB = 24 Ω
1/R = 1/24 + 1/24
or 1/R = 2/24
R = 12 Ω
Total resistance of parallel combination, R = 12 Ω
Now, V = IR
220 = 12 I
I = 18.33 A
APPEARS IN
संबंधित प्रश्न
Complete the following :-
(b)
With a neat labelled diagram and derive the equation for three resistances connected in parallel.
An electric lamp of 100 Ω, a toaster of resistance 50 Ω, and a water filter of resistance 500 Ω are connected in parallel to a 220 V source. What is the resistance of an electric iron connected to the same source that takes as much current as all three appliances, and what is the current through it?
Show how would you join three resistors, each of resistance 9 Ω so that the equivalent resistance of the combination is
1) 13.5
2) 6 Ω
Find the current in each resistor in the circuit shown below:
In the circuit given below:
(a) What is the combined resistance?
(b) What is the p.d. across the combined resistor?
(c) What is the p.d. across the 3 Ω resistor?
(d) What is the current in the 3 Ω resistor?
(e) What is the current in the 6 Ω resistor?
In the diagram shown alongside, the cell and the ammeter both have negligible resistance. The resistors are identical.
With the switch K open, the ammeter reads 0.6 A. What will be the ammeter reading when the switch is closed?
Two resistances when connected in parallel give resultant value of 2 ohm; when connected in series the value becomes 9 ohm. Calculate the value of each resistance.
You are given three resistances of 1, 2 and 3 ohms. Shows by diagrams, how with the help of these resistances you can get:
(i) 6 Ω
(ii) `6/1` Ω
(iii) 1.5 Ω
State how are the two resistors joined with a battery when potential difference is same across each resistor.
Five resistors, each 3 Ω, are connected as shown in Fig. Calculate the resistance
- between the points P and Q.
- between the points X and Y.
A battery of e.m.f 16 V and internal resistance 2 Ω is connected to two resistors 3Ω and 6Ω connected in parallel. Find:
- the current through the battery.
- p.d. between the terminals of the battery,
- the current in 3 Ω resistors,
- the current in 6 Ω resistor.
A cell supplies a current of 1.2 A through two 2Ω resistors connected in parallel. When the resistors are connected in series, if supplies a current of 0.4 A. Calculate the internal resistance and e.m.f of the cell.
Two resistors of resistance 4 Ω and 6 Ω are connected in parallel to a cell to draw 0.5 A current from the cell.
Draw a labeled diagram of the arrangement
A particular resistance wire has a resistance of 3 ohm per meter. Find the potential difference of the battery which gives a current of 2 A in each of the 1.5 m length when connected in the parallel to the battery (assume that resistance of the battery is negligible).
A current of 2 A is passed through a coil of resistance 75 Ω for 2 minutes.
(a) How much heat energy is produced?
(b) How much charge is passed through the resistance?
How does the resistance of a metallic wire depend on the length of wire?
The diagram above is a schematic diagram of a household circuit. The house shown in the above diagram has 5 usable spaces where electrical connections are made. For this house, the mains have a voltage of 220 V and the net current coming from the mains is 22A.
- What is the mode of connection to all the spaces in the house from the mains?
- The spaces 5 and 4 have the same resistance and spaces 3 and 2 have respective resistances of 20Ω and 30Ω. Space 1 has a resistance double that of space 5. What is the net resistance for space 5.
- What is the current in space 3?
- What should be placed between the main connection and the rest of the house’s electrical appliances to save them from accidental high electric current?
You have three resistors of values 2 Ω, 3 Ω, and 5 Ω. How will you join them so that the total resistance is less than 1 Ω? Draw a diagram and find the total resistance.
