Tila Tequila

Battery Voltage on BMW 525?

Ok so I’ve been having flashing lights and wasn’t sure if it was the battery or alternator. I borrowed my friends multimeter and tested the battery with the car off at 12.15 volts. Started the car and it jumps from 13.5 to 14.6 constantly. I checked the groundstrap and its secure. It looks like i may need a new battery but is this constant voltage change ok?

Two scales on a voltmeter?

Two scales on a voltmeter, which is constructed from a galvanometer, measure voltages up to 24 V and 32 V respectively. The resistance connected in series with the galvanometer is 1655 for the 24 scale and 2594 for the 32 scale.
Find the full-scale current of the galvanometer. (The full-scale current is the same in both scales.)
Answer to 2 s.f.

Where to buy Photography Filters?

Hi! So I am an ammeter photographer, and I want to purchase some photography filters, in specific IR filters. Where can I buy these? Do big shops like Best Buy and Future Shop sell these? I don’t think so… But where can I get them for a good price? Thank you so much!

Measuring resistance of wire?

I tried measuring a few cm of a wire with a multimeter and the resistance turned out to be 26 ohms and when i measured about a foot of the wire the resistance was about the same.Isnt the resistance supposed to be higher as the length of the wire increases? and i tried connecting the two wires of the multimeter and the resistance was about 25 ohms.Am i supposed to minus that reading off or is my multimeter faulty?

what\’s wrong with my Bronco?

The last two days my dash voltmeter was reading low but the truck ran fine and then occasionally so would the volt reading. As I drove tonight my truck began to chug. It felt like my truck had no power especially when I gave it gas. I drove for a few miles pulled over noticed it was fine in neutral and reverse but not in park or drive. It soon died and refused to start and a jump start did nothing. when I go to start it it will turn briefly then make a series of clicking noises and do nothing. Any ideas? Alternator? starter? Transmission?

How to test for ground loop using multimeter?

I am experiencing a hum in my audio line from my computer. I suspect it’s from a ground loop. My monitor (which house the speakers) is a 2 prong plug is plugged into a separate outlet from the power strip of which the PC is plugged into. I thought this prevents a ground loop but I would still like to test.

I just got a multimeter, and I have no idea how to use it. All the examples I see on ground loop testing are not for PC/Monitor jacks.

Can anyone give me a step by step. I have this multimeter: http://www.amazon.com/Sinometer-Manual-Digital-Multimeter-MS8268/dp/B000JQ4O2U?SubscriptionId=02B7Y8VZ2ZRE5MXHPMR2&tag=vglnk-c1001-20&linkCode=xm2&camp=2025&creative=165953&creativeASIN=B000JQ4O2U

The total internal resistance of an ohmmeter having a 5V internal battery and using a 1mA meter movement is?

A. 2000 ohms
B. 3000 ohms
C. 4000 ohms
D. 5000 ohms

A voltmeter with a 20V full scale indication at 1mA has an internal resistance of 1500 ohms. What multiplier resistor value is required for the voltmeter?
A. 20000 ohms
B. 18500 ohms
C. 2000 ohms
D. 1850 ohms

A 0-1 mA meter with an internal resistance of 1000 ohms is converted to a 0-10mA meter.
What is the value of shunt resistance needed for full-scale deflection at 10mA?
A. 144.4 ohms
B. 111.1 ohms
C. 0.144 ohms
D. 0.111 ohms

An ohmmeter is connected in…
A. Series with the component being measured
B. Parallel with the voltage source
C. Series/parallel to the circuit
D. Parallel with the component being measured

A voltmeter uses a 1mA, 1500 ohms meter movement. What total circuit resistance is required for a 20V full scale indication?
A. 20 ohms
B. 200 ohms
C. 2000 ohms
D. 20000 ohms

To connect an ammeter in a circuit…
A. Open the circuit at one point and insert the ammeter to complete the circuit.
B. Attach the test leads across the component to be measured
C. Remove the power from the circuit
D. Attach the test leads across the voltage source

An ohmmeter is adjusted for zero ohms when
A. The test leads are shorted
B. The test leads are open
C. A known resistance is measured
D. Circuit power is off

A multiplier for a voltmeter is…
A. A high resistance in parallel with the meter movement
B. Usually less than the meter resistance
C. A high Resistance in series with the meter movement
D. Usually equal to the meter Resistance

A milliammeter shunt…
A. Decreases the range
B. Is connected in series with the meter
C. Increases the range
D. converts the meter to a voltmeter

What is the current flowing in an ohmmeter when it indicates infinite Resistance
A. Minimum
B. Maximum
C. Halfway between minimum and maximum
D. None of the above

Please answer as many questions as you can. It would really mean a lot to me if you could me with these questions.
Thanks

LED and resistor help.?

Ok, I have a 149 mcd – 5mm BLUE LED
3.8Vf @ 20mA

I want to use this LED as my power LED for the motherboard of a custom pc I’m building. Using a multimeter, I get a reading of 5V from the motherboard PWR LED header. I used the following formula to calculate the resistor needed to power my LED:

R = (Vs – VL) / I

I plugged in my numbers:

R = (5V – 3.8V) / 0.02A (= 60 Ohms.)

Therefore, I calculated I need 60 Ohms of resistance to properly power this LED. I just happened to have a 68 Ohm 1/8W resistor. I soldered the resistor to the positive lead of the LED and then wired the LED to the motherboard. The LED lit up perfectly fine!

Now here’s where I get lost. When I check the voltage after the resistor, I’m still getting a reading of 5V. Shouldn’t the resistor be lowering the voltage? What’s the point of the resistor if I’m getting 5V to the LED with AND without it?

which way does the direction of voltage go in electromagnetic(GCSE)?

I don’t understand which way the direction of the voltage depends on. I mean if you put the magnet into a coil of wire and the magnet is put in at south which way does it go on the voltmeter i.e postivie or negative and also why?
Please answer the question basically don’t copy stuff from wiki
Thanks for your help.

voltmeter reads 10V when a resistance R1 is connected. it is 8V when 20 ohm resistance R2 is connected.?

what is the internal resistance of the battery????