Electrical resistance Questionschool experiement ?

Click For Summary
SUMMARY

This discussion focuses on the behavior of voltmeters in RC circuits, specifically regarding their internal resistance. It is established that the internal resistance of a voltmeter, such as one with a 10 V maximum reading, remains constant regardless of the potential difference (pd) measured, exemplified by a resistance of 100,000 ohms at 10 V. When measuring higher voltages, such as 20 V, the user must switch to a higher range, which alters the internal resistance to 200,000 ohms. The ohm/volt value of the voltmeter is a fixed characteristic of the device and does not change with the voltage range selected.

PREREQUISITES
  • Understanding of RC circuits
  • Knowledge of voltmeter operation and characteristics
  • Familiarity with potential difference (pd) measurements
  • Basic principles of electrical resistance
NEXT STEPS
  • Research the principles of RC circuit analysis
  • Learn about different types of voltmeters and their specifications
  • Study the concept of internal resistance in measuring instruments
  • Explore the effects of range switching on measurement accuracy
USEFUL FOR

Students conducting experiments in electronics, educators teaching electrical engineering concepts, and anyone interested in understanding voltmeter functionality and resistance in circuits.

cowboi12345
Messages
7
Reaction score
0
I'm doing this investigation on RC circuits...we had to find the experimental resistance value of a resistor connected with in the circuit...and a volt meter was connected in parallel with the capictor and resistor...this question is regarding the resistance of the voltmeter...according to the information we were given, if 10v of pd passes through the voltmeter, the resistance is 100000ohms...so if 20v of pd passes through the voltmeter...would the resistance be 200000ohms?
 
Physics news on Phys.org
The internal resistance of the voltmeter does not depend on the measured pd, but changes when you switch over the range. The ohm/volt value of a classical voltmeter is characteristic to the apparatus and does not change when you switch to an other voltage range. It is the maximum reading over the internal resistance. In case the meter is set to 10 V maximum reading, and then the internal resistance is 1000000 ohm, the ohm/volt value is 10000 for that meter. The internal resistance is the same regardless the measured pd, it is 100000 ohm at 1 V or 5 V or 10 V...
If you want to measure a pd higher than 10 V you need to switch to a higher range. The ohm/volt value of the meter is 10000. If there is a 20 V range, the internal resistance is 200000 ohm here.

ehild
 
ehild said:
The internal resistance of the voltmeter does not depend on the measured pd, but changes when you switch over the range. The ohm/volt value of a classical voltmeter is characteristic to the apparatus and does not change when you switch to an other voltage range. It is the maximum reading over the internal resistance. In case the meter is set to 10 V maximum reading, and then the internal resistance is 1000000 ohm, the ohm/volt value is 10000 for that meter. The internal resistance is the same regardless the measured pd, it is 100000 ohm at 1 V or 5 V or 10 V...
If you want to measure a pd higher than 10 V you need to switch to a higher range. The ohm/volt value of the meter is 10000. If there is a 20 V range, the internal resistance is 200000 ohm here.

ehild

Thanks! :-)
 

Similar threads

  • · Replies 1 ·
Replies
1
Views
839
  • · Replies 2 ·
Replies
2
Views
758
Replies
4
Views
2K
  • · Replies 14 ·
Replies
14
Views
2K
  • · Replies 31 ·
2
Replies
31
Views
5K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
Replies
14
Views
2K