Advertisements
Advertisements
Question
What is (a) highest, and (b)Ω lowest, resistance which can be obtained by combining four resistors having the following resistances?
4 Ω, 8 Ω, 12 Ω, 24 Ω
Advertisements
Solution
(a) To get the highest resistance, all the resistors must be connected in series.
Resistance in a series arrangement is given by R = R1+ R2 + R3 + R4
R=4Ω+8Ω+12Ω+24Ω
R=48Ω
Therefore, the highest resistance is 48 Ω.
(b) To get the lowest resistance, all the resistors must be connected in parallel.
Resistance in a parallel arrangement is given by:
`1/R=1/R_1+1/R_2+1/R_3+1/R_4`
Here`R_1=4`Ω
`R_2=8` Ω
`R_3=12` Ω
`R_4=24`Ω
`1/R=1/4+1/8+1/12+1/24`
`1/R=(6+3+2+1)/24`
`1/R=12/24`
R=2Ω
Therefore, the lowest resistance of the arrangement is 2 Ω.
APPEARS IN
RELATED QUESTIONS
Why is the series arrangement not used for domestic circuits?
Name the material which is used for making the heating element of an electric iron.
Draw a V-I graph for a conductor at two different temperatures. What conclusion do you draw from your graph for the variation of resistance of conductor with temperature?
State how are the two resistors joined with a battery when same current flows in each resistor.
What potential difference is needed to drive a current o f 1 A through a 5 Ω resistor?
To increase the effective resistance in a circuit, the resistors are connected in _______________ .
When do you say that the resistors are connected in this way? Draw a circuit diagram.
Answer the following question.
While studying the dependence of potential difference ( V) across a resistor on the current (I) passing through it, in order to determine the resistance of the resistor, a student took 5 readings for different values of current and plotted a graph between V and t. He got a straight line graph passing through the origin. What does the straight-line signify? Write the method of determining the resistance of the resister using this graph.
State expression for Resistance connected in parallel.
Illustrate-combination of cells e.g., three cells, in series, explaining the combination briefly. Obtain an expression for current ‘i’ in the combination.
Calculate the value of the resistance which must be connected to a 15 ohm resistance to provide on effective resistance of 6 ohm.
Two wires of same material and same lengths have radii in the ratio of 2 : 3, Compare their resistances.
Two resistors having 2Ω and 3Ω resistance are connected—(i) in series, and (ii) in parallel. Find the equivalent resistance in each case.
In an electrical circuit, two resistors of 2 Ω and 4 Ω respectively are connected in series to a 6 V battery. The heat dissipated by the 4 Ω resistor in 5 s will be ______.
Two electric bulbs have resistances in the ratio 1 : 2. If they are joined in series, the energy consumed in them is in the ratio:
