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  #1  
Old 03-09-2009, 04:33 AM
salmanshaheen_88 salmanshaheen_88 is offline
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Default A small problem

How to find current in 750Ω resistor.I know it can be solved by using superposition and thevenin theorem but don't know how to apply.Your help is needed till end step.Answer given at the end of book is 9mA. Remember it's not a homework it's a general practice.
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Old 03-09-2009, 05:42 AM
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thatoneguy thatoneguy is offline
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You will need to write simultaneous equations to solve for the unknown voltages/current. Simplify it to a single resistor in parallel with the current sink, both of which are in series with the 1.5k resistor and supply.

Once the voltage drop across the series 1.5k resistor is found, the rest of the currents are found by simple division of the remaining voltage by the resistance.
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Old 03-09-2009, 05:43 AM
t_n_k t_n_k is offline
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Hello Salmanshaheen_88,

One approach ...

Applying superposition ...

1. Remove the current source and work out the current and its direction in the 750Ω where the voltage source alone supplies the current. The voltage source drives a series-parallel combination. Record this value [I1].

2. Replace the voltage source with a short circuit and work out the current and its direction in the 750Ω where the current source alone supplies the current.

3. Add the value found in step 2 [I2] to the value found in step 1 above [I1]. Pay careful attention to the current direction for each case - I1 may be flowing downwards while I2 may be flowing upwards.

Give it a go and respond if you are still stuck. Good luck.

Refer to Vol. 1 - DC on this site for all of the above techniques and more ....
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Old 03-09-2009, 06:03 AM
salmanshaheen_88 salmanshaheen_88 is offline
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ok I solved it thanks to u guyz
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