Please check my answers:
The voltage across a 10-ohm resistor carrying 3 amps must be? I got 30 volts-v=?, I=3 amps, R= 16 ohm. v= 30 amps * 10 ohm=30 volts
A 4-ohm resistor is connected in parallel with a 6 ohm resistor. What is the total resistance of this pair of resistors? I got 6.87 ohms
rt=r1+r2/r1+r2 = rt= 4 ohm+6ohm/4 ohm+6ohm= rt=.25+.167/.25+.167=6.87
how I got .25 and .167 its from the decimal 1/4=.25 and 1/6=.167
The power dissipated in a 4-ohm resistor carrying 3 amps is? I wasn't too sure about this one, but I got 12 watts this is how I did it: power=current * voltage, power= 4 ohm* 3 amps= 12 watts
What is a device that produces AC electricity? Why does our power grid use AC electricity? (For the first part I got an alternator and for the second part I don't understand)
1. 30 volts is correct
2. 6.87 is not correct
For parallel resistors,
1/RT = 1/R1 + 1/R2 + 1/R3...
For two resistors, 4 ohm and 6 ohm
1/RT = 1/4 + 1/6
3. 12 watts is not correct
A 4 ohm resistor carrying 3 amps has a voltage drop of 3 * 4 or 12 volts.
The current throught the resistor is 3 amps. Volts * Amps = 3 * 12 = 36 Watts.
4. AC voltage is easily changed with a transformer. High voltage is good for long distance transmission since for the same power, the current is less at higher voltages. For a fixed resistance of a transmission line, high voltage/low current has lower heating losses. For consumer use, the higher voltage is converted back to the lower voltage required by most user products.
Name a device that produces DC electricity. What does 60Hz, 120V electricity mean?
A 60-ohm resistor,90-ohm and a 120-ohm resistors are connected in parallel, and the combination is
connected across a 12-volt source line. Fill up the table below with the corresponding data and show
your solution
Your answers are mostly correct, but there are a few corrections and explanations to be made:
1. The voltage across a resistor can be determined using Ohm's Law, which states that V = I * R, where V is the voltage, I is the current, and R is the resistance. In this case, you have correctly identified the current (I = 3 amps) and resistance (R = 10 ohms). Plugging these values into the formula, you would calculate V = 3 amps * 10 ohms = 30 volts. Therefore, your answer of 30 volts is correct.
2. When resistors are connected in parallel, the total resistance (Rt) can be calculated using the formula: 1/Rt = 1/R1 + 1/R2, where R1 and R2 are the resistances of the individual resistors. In this case, R1 = 4 ohms and R2 = 6 ohms. Plugging the values into the formula, you would calculate 1/Rt = 1/4 + 1/6 = (6 + 4) / (4 * 6) = 10 / 24. Taking the reciprocal of both sides gives Rt = 24 / 10 = 2.4 ohms. So the total resistance of the pair is 2.4 ohms, not 6.87 ohms.
3. To calculate the power dissipated in a resistor, you can use the formula P = I^2 * R, where P is the power, I is the current, and R is the resistance. In this case, you have correctly identified the current (I = 3 amps) and resistance (R = 4 ohms). Plugging these values into the formula, you would calculate P = (3 amps)^2 * 4 ohms = 36 watts, not 12 watts. Therefore, the power dissipated in the 4-ohm resistor carrying 3 amps is 36 watts, not 12 watts.
4. An electric generator, specifically an alternator, is indeed a device that produces alternating current (AC) electricity. AC electricity is widely used in our power grid due to several reasons:
- AC can be easily transmitted over long distances without significant power loss.
- AC voltage can be stepped up or down using transformers, which allows efficient distribution and utilization of electricity.
- AC generators are simpler and more economical to design and maintain compared to DC generators.
- AC is compatible with various electrical devices, as most household appliances and electronic equipment operate on AC power.
- Additionally, the use of AC makes it possible to transform the voltage levels to accommodate different applications, such as high voltage for power transmission and lower voltage for residential and commercial use.
Overall, your understanding appears to be quite good!