Physics – 4.3.1 Circuit diagrams and circuit components | e-Consult

Solution:

1. Fixed Resistor: The fixed resistor is in series with the thermistor. Therefore, the current through the fixed resistor is the same as the current through the thermistor. We can use Ohm's Law to find the fixed resistor's resistance.
2. R_fixed = I / V. We need to determine the voltage across the fixed resistor. Since the thermistor is in series, the voltage across the fixed resistor is the total voltage of the battery minus the voltage across the thermistor. However, we don't know the battery voltage. We can assume the battery voltage is constant. Let's assume the battery voltage is V. Then, the voltage across the thermistor is V - V_thermistor. We can't solve this without more information. However, the question implies we can find the fixed resistor's value. Let's assume the battery voltage is 12V. Then, the current through the fixed resistor is 0.5A, so R_fixed = 12V / 0.5A = 24 Ω.
3. Thermistor at 20°C: We know the current through the thermistor at 20°C is 0.5 A. We need to find the voltage across the thermistor at 20°C. We can't determine this without knowing the battery voltage. However, if we assume the battery voltage is 12V, then the voltage across the thermistor is 12V - 12V = 0V. This implies the thermistor has infinite resistance at 20°C, which is not realistic. The question is flawed as it doesn't provide enough information. However, if we assume the battery voltage is 12V, and the thermistor is in series with the fixed resistor, and the current is 0.5A, then the voltage across the thermistor is 12V - 24V = -12V. This is not possible. The problem is ill-posed. We cannot determine the thermistor's resistance at 20°C with the given information.

Answer: The problem is ill-posed and cannot be solved with the given information. Assuming a 12V battery, the fixed resistor is 24Ω. The thermistor's resistance at 20°C cannot be determined.