can you please check my answers and help me with one question?
During a lie dector test, a voltage of 6 V is impressed across two fingers. When a certain question is asked, the resistance between the fingers drops from 400,000 ohms to 200, 000 ohms. What is the current (a) initially through the fingers, and (b) when the resistance between them drops? (this question I don't understand)
How much resistance allows an impressed voltage of 6V to produce a current of 0.006 A ? I got 1000 ohm
What is the resistance of a clothes iron that draws a current of 12 A at 120 V? I got 10 ohm
The current in an incandescent lamp is 0.5A when connected to a 120-V circuit, and 0.2A when connected to a 10-V source. Does the resistance of the lamp change in these cases? Explain your answers and defend it with numerical values?( I got: 120 V/0.5A=240 ohms and 10V/0.2A=50 ohms. Yes the resistance changes in both cases.)
duplicate post
To find the current, you can use Ohm's Law, which states that current (I) is equal to voltage (V) divided by resistance (R).
(a) Initially, the resistance is 400,000 ohms, so to find the initial current, you can use the equation I = V/R. Plugging in the values, we have I = 6 V / 400,000 ohms = 0.000015 A.
(b) When the resistance drops to 200,000 ohms, you can again use Ohm's Law to find the current. I = V/R = 6 V / 200,000 ohms = 0.00003 A.
For the second question, you are given a voltage of 6V and a current of 0.006 A. To find the resistance, you can rearrange Ohm's Law to solve for R. R = V/I = 6 V / 0.006 A = 1000 ohms. So your answer is correct.
For the third question, you are given a current of 12 A and a voltage of 120 V. To find the resistance, you again use Ohm's Law. R = V/I = 120 V / 12 A = 10 ohms. So your answer is correct.
For the fourth question, you have calculated the resistance correctly using Ohm's Law. However, the resistance does not change in both cases. The resistance of the lamp remains constant regardless of the voltage applied to it. The reason you calculated different resistance values is because the current changed due to the different voltages, not because the resistance itself changed.