Advertisements
Advertisements
Question
Differentiate between resistances in series and parallel.
Advertisements
Solution
| Resistances in Series | Resistances in Parallel | ||
| 1 | In this type of connection, the resistances are connected one after the other such that the same amount of current flows through each resistance. | 1 | In this type of connection, the resistances are connected between two common points such that the potential difference across each resistor is the same. |
| 2 | For n number of resistors connected in series, the effective resistance RS is equal to the sum of the individual resistors. RS = R1 + R2 + R3 + R4+ …… Rn |
2 |
For n number of resistors connected in pparallel, the reciprocal of the effective resistance (Rp) is equal to the sum of the reciprocals of the individual resistances. `1/R_p=1/R_1+1/R_2+..............+1/R_p`
|
| 3 | The effective resistance in series combination is greater than the individual resistances. | 3 | The effective resistance in parallel combination is less than the individual resistances in the combination. |
| 4 | It is used to decrease the current in the circuit. | 4 | It is used to increase the current in the circuit. |
APPEARS IN
RELATED QUESTIONS
What are the advantages of connecting electrical devices in parallel with the battery instead of connecting them in series?
How many 176 Ω resistors (in parallel) are required to carry 5 A on a 220 V line?
State the law of combination of resistances in parallel.
Two resistors, with resistance 5 Ω and 10 Ω respectively are to be connected to a battery of emf 6 V so as to obtain:
(i) minimum current flowing
(ii) maximum current flowing
(a) How will you connect the resistances in each case?
(b) Calculate the strength of the total current in the circuit in the two cases.
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.
A wire of resistance R1 is cut into five equal pieces. These five pieces of wire are then connected in parallel. If the resultant resistance of this combination be R2, then the ratio `R_1/R_2` is:
(a) `1/25`
(b)1/5
(c)5
(c)25
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.
How will you connect three resistors of resistances 2 Ω, 3 Ω, and 6 Ω to obtain a total resistance of 4 Ω, and 1 Ω?
If current flows through two lamps arranged:
(a) in series,
(b) in parallel,
and the filament of one lamps breaks, what happens to the other lamp? Explain your answer.
A uniform wire with a resistance of 27 Ω is divided into three equal pieces and then they are joined in parallel. Find the equivalent resistance of the parallel combination.
What are the advantages of a parallel connection?
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 particular resistance wire has a resistance of 3 ohm per meter. Find :
The total resistance of three lengths of this wire each 1.5 m long, in parallel.
An electrical appliance has a rating 100 W, 120V. The resistance of element of appliance when in use:
Calculate equivalent resistance in the following cases:
What connection is used in domestic appliances and why?
A piece of wire having a resistance R is cut into five equal parts.
- How will the resistance of each part of the wire change compared with the original resistance?
- If the five parts of the wire are placed in parallel, how will the resistance of the combination change?
- What will be ratio of the effective resistance in series connection to that of the parallel connection?
Two V-I graphs A and B for series and parallel combinations of two resistors are as shown. Giving reason state which graph shows (a) series, (b) parallel combination of the resistors.
