As shown in figure a, it is a schematic diagram of using thermistor to measure temperature. In this diagram, the temperature to be measured can be reflected not only by the indication of ammeter, but also by the indication of voltmeter. It is known that the power supply voltage is 20V and remains unchanged, R0 is the constant resistance, and the resistance value is 30 Ω. The relationship between the resistance value of thermistor R and temperature is shown in Figure B (1) When the temperature to be measured increases, how does the ratio of voltage representation to current representation change? (2) When the temperature to be measured is 24 ℃, what are the indication numbers of ammeter and voltmeter? (3) It is known that the range of ammeter is 0 ~ 0.6A and that of voltmeter is 0 ~ 15V. What is the maximum temperature that this circuit can measure? What is the power consumption of thermistor r at this time?

As shown in figure a, it is a schematic diagram of using thermistor to measure temperature. In this diagram, the temperature to be measured can be reflected not only by the indication of ammeter, but also by the indication of voltmeter. It is known that the power supply voltage is 20V and remains unchanged, R0 is the constant resistance, and the resistance value is 30 Ω. The relationship between the resistance value of thermistor R and temperature is shown in Figure B (1) When the temperature to be measured increases, how does the ratio of voltage representation to current representation change? (2) When the temperature to be measured is 24 ℃, what are the indication numbers of ammeter and voltmeter? (3) It is known that the range of ammeter is 0 ~ 0.6A and that of voltmeter is 0 ~ 15V. What is the maximum temperature that this circuit can measure? What is the power consumption of thermistor r at this time?

(1) The ratio of voltmeter and ammeter is the resistance value of R0, which is constant; (2) the image shows that at 24 ℃, r = 50 Ω, according to Ohm's law, I = ur + R0 = 20v50 Ω + 30 Ω = 0.25A, so the current representation is 0.25A and U0 = ir0 = 0.25A × 30 Ω = 7.5V, so the voltage representation is 7.5V

How to analyze which electric appliance is measured by ammeter

The ammeter measures the current in the circuit in series with it
So, just look at the ammeter in series with that part of the consumer,
Ammeter is to measure the current of this part of electrical appliances
In particular, series circuit, ammeter to measure the current of all electrical appliances!

Why can't the ammeter be paralleled in the circuit under test?
It's better to have a circuit diagram,

If it is directly connected in parallel in the circuit under test, it will cause short circuit of power supply. Because the ammeter has almost no resistance, it is equivalent to a wire. But when it is connected in parallel, it is enough to connect an electric appliance in the branch connected with the ammeter

Can the ammeter be connected in parallel with the circuit under test

It's OK under certain conditions. We say that the resistance of the ammeter is 0, which is just an ideal condition. It also has resistance. The condition of series connection is that the maximum current cannot exceed the current allowed by the ammeter, otherwise the ammeter will be burnt out