Поделиться
PHY_10_40_V1_P_Internal r.pptx
INTERNAL RESISTANCE
LO:
10.3.2.1 to explain the definition of internal resistance
PHY_10_40_V1_P_INTERNAL RESISTANCE OF THE SOURCE
REVISION QUESTIONS:
PHY_10_40_V1_P_INTERNAL RESISTANCE OF THE SOURCE
ACTIVITY 2:
PHY_10_40_V1_P_INTERNAL RESISTANCE OF THE SOURCE
a
b
c
d
Circuit a | Circuit b | Circuit c | Circuit d |
V= | |||
R=100Ohm | R=10Ohm | R=1Ohm | |
RESULTS of the observation
PHY_10_40_V1_P_INTERNAL RESISTANCE OF THE SOURCE
Why the reading of the voltmeters in each case different?
https://www.youtube.com/watch?v=k077CwKGiwk
Work in pairs:
PHY_10_40_V1_P_INTERNAL RESISTANCE OF THE SOURCE
As we decrease the resistance, voltage across the resistor is decreases. WHY?
That is because of internal resistance (r).
Discussion of results
PHY_10_40_V1_P_INTERNAL RESISTANCE OF THE SOURCE
Why the battery has an Internal Resistance
Batteries have internal resistance because the elements that make it up aren't perfect conductors. The electrodes and electrolytes aren't 100% conductive. So they will have some resistance (internal resistance) in them.
Ideally, a battery should have 0Ω internal resistance. So during battery operation, all the voltage will be dropped across the element that the battery is powering instead of the battery dropping voltage across itself. According to voltage division, voltage drops across the element with the higher impedance. Ohm's law tells you this in V=IR, showing the higher the resistance, the greater the voltage drop. So if a battery has 0Ω of resistance and it will power a device that has at least some impedance, this ensures, according to ohm's law, that the device will get the voltage and not the battery. This is the ideal case but it doesn't occur in real life.
What if Internal Resistance of the battery is ZERO
PHY_10_40_V1_P_INTERNAL RESISTANCE OF THE SOURCE
Without any load, we can meaure the open-circuit voltage of the battery by placing a multimeter on the DC voltage setting to measure voltage.
if we attach a load to the battery, the output terminal voltage of the battery drops. By treating the internal resistance Rin and the load resistance RLoad as a voltage divider, you can calculate the true output voltage presence across the load.
INTERNAL RESISTANCE in an open and closed circuit
PHY_10_40_V1_P_INTERNAL RESISTANCE OF THE SOURCE
Batteries with large internal resistance show poor performance in supplying high current pulses.
This is because current is decreased with higher resistance. Current equals voltage divided by resistance (i=v/r). So the higher the internal resistance, the lower the current output ability. Low internal resistance batteries are much better at supplying high current pulses.
Internal resistance also increases as the battery discharges. Therefore, a typical alkaline AA battery may start out with an internal resistance of 0.15Ω but may increase to 0.75Ω when 90 percent discharged.
WHAT is better:
low internal resistance or high
PHY_10_40_V1_P_INTERNAL RESISTANCE OF THE SOURCE
Batteries will always have some resistance. Though the internal resistance may be or appear low, around 0.1Ω for an AA alkaline battery, and about 1Ω to 2Ω for a 9-volt alkaline battery, it can cause a noticeable drop in output voltage if a low-resistance load is attached to it.
Batteries internal resistances
PHY_10_40_V1_P_INTERNAL RESISTANCE OF THE SOURCE
Материалы на данной страницы взяты из открытых источников либо размещены пользователем в соответствии с договором-офертой сайта. Вы можете сообщить о нарушении.
