Voltage - StudentOfFortune.com

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Surferchick11587
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$1.00 Voltage

From Physics: General-Physics
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Due on Jul. 22, 2009
Asked on Jul 19, 2009 at 5:58:00PM

Q:
1. If the voltage across a 1.2-k resistor is 3.6 V, what is the current (in mA) flowing through it?

2. A 1.5-V battery is connected in series with a 3.3-k resistor, a 4.7-k resistor, and a 1.0-k
resistor. Calculate the current (in mA) through and the voltage (in V) across each resistor.

3. What is the effective resistance of a series combination of a very large resistance and a very small
resistance? First try 10 k and 10 , rounding the answer off to two significant figures, to get a
feel for what is happening, and then state the general rule for finding the result given any large and
small resistances, not necessarily these exact two values. If used as a voltage divider connected
across a 1.5-V battery, approximately what will be the potential drop across each resistor?

4. What is the effective resistance of a parallel combination of a very large resistance and a very
small resistance? First try 10 k and 10 , and then generalize the result. If connected to a power
supply delivering 100 mA of current, approximately what will be the current through each resistor?

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nearlyalex
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Posted on Jul 19, 2009 at 7:00:14PM

A:
Preview: ... age law says that the voltage charges around any closed loop must sum to zero. So we know the drop over a resistor is given by V = IR from ohm’s law So V1 = I R1 = (0.17*10^-3)*3.3*10^3 = 0.55 V V2 = I R2 = (0.17*10^-3)*4.7*10^3 = 0.78V V3 = I R3 = (0.17*10^-3)*1.0*10^3 = 0.17 V 3. What is the effective resistance of a series combination of a very large resistance and a very small resistance? R(total) = R(vary large) + R(very small) ~ R(very large) As R(vary large) >> R(very small) In series the total resistance is the sum of the resistances and as the very large one is much greater than the very small resistances the total is approximately equal to the very large. First try 10 k and 10 , rounding the answer off to two significant figures, to get a feel for w ...

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Posted on Jul 19, 2009 at 7:15:36PM

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Preview: ... ms Req = 9000 ohms V = IR I = V / R I = 1.5 V / 9000 ohms I = 1.67 x 10^-4 Amps = 0.167 mA --> Answer V1 = I(R1) V1 = (1.67 x 10^-4 Amps)(3300 ohms) V1 = 0.55 V --> Answer V2 = (1.67 x 10^-4 Amps)(4700 ohms) V2 = 0.783 V --> Answer V3 = (1.67 x 10^-4 Amps)(1000 ohms) V3 = 0.167 V --> Answer Notice that V1 + V2 + V3 = Vbattery ...

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Posted on Jul 19, 2009 at 10:34:41PM

A:
Preview: ... 9 = 1/6 mA = 0.167 mA Solution#3 effective resistance of a series combination of a very large resistance and a very small resistance is nearly equal to large resistance. Voltage = v = 1.5 ...

The full tutorial is about 159 words long .