A 10 ohms resistor has a constant current. If 1200C of charge flow through it in 4 minutes what is the value of the current?
A) 3.0 A
B) 5.0 A
C) 11 A
D) 15 A
E) 20 A
ok I see to main equation using dealing with resistance I=V/R and I=Q/t. My question deals with how would I factor in the resistance to get the correct answer. I used the I=Q/t, 1200C/240s to get 5A which is an answer but I am unsure how to place the resistance in.
In a conductor carrying a current we expect the average electron velocity to be:
a) much greater than average electron speed
b) much less than average electron speed
c) about the same as the average electron speed
d) less than average electron speed at low temp and greater at high temp
e) less than average at high temp and greater than the average at low
I choose B due to resistance and what I posted:
All conductors contain movable electric charges which will move when an electric potential difference (measured in volts) is applied across separate points on a wire made from the material. This flow of charge in amperes) is what is meant by electric current. In most materials, the amount of current is proportional to the voltage (Ohm's Law) provided the temperature remains constant and the material remains in the same shape and state. The ratio between the voltage and the current is called the resistance (measured in ohms) of the object between the points where the voltage was applied.
Thank you :)
Welcome to Jiskha and thanks for posting your thoughts along with your questions. Both of your answers are correct and demonstrate your understanding and thought process. That helps us help you.
Your first question provided more information than was need to answer the question. All that you needed was I = Q/t. Selecting the data you need and ignoring the rest is an important skill that you are learning well.
The second question could have been answered most simply by saying that the velocity of electrons in conductors is highly random in direction. The avergage speed of the electrons is high, but only a small fraction contributes to the component in the direction of the electric field and the current.
To solve the first question, you can use the equation I = Q/t, where I is the current, Q is the charge, and t is the time. You correctly used this equation to calculate the current as 5A.
To factor in the resistance, you can use Ohm's Law, which states that the current flowing through a resistor is equal to the voltage across the resistor divided by its resistance (I = V/R). In this case, you are given the resistance of 10 ohms.
To use Ohm's Law, you need to find the voltage across the resistor. The voltage can be calculated using the equation V = Q/C, where V is the voltage, Q is the charge, and C is the capacitance. However, in this case, you are not given the capacitance value, so this equation is not applicable.
Since you already know the current (5A) and the resistance (10 ohms), you can use the equation I = V/R to find the voltage across the resistor. Rearranging the equation, V = I * R, gives you V = 5A * 10 ohms = 50 volts.
So, the value of the current is 5A, and the voltage across the resistor is 50 volts.
As for the second question, the correct answer is e) less than average at high temp and greater than the average at low. This is because the average speed of electrons in conductors is relatively high, but their average velocity in the direction of the electric field (which determines the current) is lower. At higher temperatures, the increased thermal energy leads to greater random motion of the electrons, decreasing their average velocity in the direction of the electric field.