Advertisements
Advertisements
प्रश्न
State the law of combination of resistances in parallel.
Advertisements
उत्तर
In a parallel combination, the voltage remains the same across each resistor but the current gets divided. Let I1, I2 and I3 be the current across resistors R1, R2 and R3, respectively.
`l=l_1+l_2+l_3`
`V=LR,V=L_1R_1,L_2R_2, V=L_3R_3`
`I=v/R,I_1 V/R_1, I_2=V/R_2,L_3 V/R_1`
Using thrsr value, We get:
`V/R=V/R_1+V/R_2+V/R^1`
`1/R=1/R_1+1/R_2+1/R_1`
So, the total resistance is the sum of the reciprocal of the individual resistances.
APPEARS IN
संबंधित प्रश्न
How can three resistors of resistances 2 Ω, 3 Ω and 6 Ω be connected to give a total resistance of 4 Ω ?
A hot plate of an electric oven connected to a 220 V line has two resistance coils A and B, each of 24 Ω resistances, which may be used separately, in series, or in parallel. What are the currents in the three cases?
A wire that has resistance R is cut into two equal pieces. The two parts are joined in parallel. What is the resistance of the combination?
Explain with diagram what is meant by the "series combination" and "parallel combination" of resistances. In which case the resultant resistance is : (i) less, and (ii) more, than either of the individual resistances?
A resistor of 8 ohms is connected in parallel with another resistor X. The resultant resistance of the combination is 4.8 ohms. What is the value of the resistor X?
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.
In the following figure calculate:
- the total resistance of the circuit
- the value of R, and
- the current flowing in R.
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 battery of e.m.f. 15 V and internal resistance 2 `Omega` is connected to tvvo resistors of 4 ohm and 6 ohm joined.
(i) In series,
(ii) In para 1 lel. Find in each case the electrica I energy spent per minute in 6 ohm resistor.
Tick (✓) the correct choice among the following :
Consider two cases of two parallel current carrying conductors. Current in
th e same direction and currents in th e opposi te directions will produce
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.
The circuit diagram Fig shows three resistors 2 Ω, 4 Ω and R Ω connected to a battery of e.m.f. 2 V and internal resistance 3 Ω. If main current of 0.25 A flows through the circuit, find:
- the p.d. across the 4 Ω resistor,
- the p.d. across the internal resistance of the cell,
- the p.d. across the R Ω or 2 Ω resistors
- the value of R.
An electrical appliance has a rating 100 W, 120V. The resistance of element of appliance when in use:
The equivalent resistance of a parallel combination of two resistors of 30 Ω and 60 Ω is ______________.
How does the resistance of a metallic wire depend on the thickness of wire?
Calculate equivalent resistance in the following cases:
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?
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.
Two resistors of resistances 2 Ω and 3 Ω are connected in parallel to a cell to draw current 0.5 A from the cell. Draw a labelled diagram of the arrangement
