Rankers Physics
Topic: Capacitors
Subtopic: Combination of Capacitors

Minimum number of 8 μF and 250 V capacitors used to make a combination of 16 μF and 1000 V are:
32
16
8
4

Solution:

To solve this, we determine the combination of capacitors required to achieve the desired capacitance and voltage.


Given:

  • Individual capacitor:
    C=8μFC = 8 \, \mu\text{F}
     

    , Vmax=250VV_{\text{max}} = 250 \, \text{V} 

  • Desired combination:
    Creq=16μFC_{\text{req}} = 16 \, \mu\text{F}
     

    , Vreq=1000VV_{\text{req}} = 1000 \, \text{V} 


Step 1: Voltage requirement

To achieve

Vreq=1000VV_{\text{req}} = 1000 \, \text{V}

, multiple capacitors must be connected in series because the voltage across a series combination adds up. The number of capacitors required in series is:

 

n=VreqVmax=1000250=4n = \frac{V_{\text{req}}}{V_{\text{max}}} = \frac{1000}{250} = 4

 

Thus, 4 capacitors in series are required to handle 1000 V.


Step 2: Capacitance in series

The effective capacitance of

nn

capacitors in series is given by:

 

Cseries=Cn=84=2μFC_{\text{series}} = \frac{C}{n} = \frac{8}{4} = 2 \, \mu\text{F}

 

So, a series of 4 capacitors provides

Cseries=2μFC_{\text{series}} = 2 \, \mu\text{F}

.


Step 3: Capacitance requirement

To achieve

Creq=16μFC_{\text{req}} = 16 \, \mu\text{F}

, multiple such series groups must be connected in parallel because capacitance in parallel adds up. The number of such series groups required is:

 

m=CreqCseries=162=8m = \frac{C_{\text{req}}}{C_{\text{series}}} = \frac{16}{2} = 8

 

Thus, 8 series groups are required.


Step 4: Total capacitors

Each series group contains 4 capacitors, and there are 8 such groups. Therefore, the total number of capacitors is:

 

Total capacitors=nm=48=32\text{Total capacitors} = n \cdot m = 4 \cdot 8 = 32

 


Final Answer:

The minimum number of capacitors required is:

 

32\boxed{32}

 

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