I am so confused about this ampere thing.

Here are my questions.

1.A DC battery can deliver any amount of electric current we want(Before the battery burns out).For example, an led with 5 voltage and 1 amp rating can work in a battery of 9 v and a motor with the same voltage but higher ampere can also work in this battery.Right?

2.In the phone adapter(I am trying to charge my iPhone from a car igniter.), it is said to deliver 5v at 1A.Here why do they even mention the ampere if it is not needed and it all depends on the phone itself(I am thinking why can't the phone take ampere it needed like the led.I am not giving specific current to led.It is taking what is needed.)

3.Is it safe to measure the ampere of the phone adapter(Which is said to deliver 1 A of current) with my multimeter?(I tried to measure ampere of a battery and the multimeter went crazy.)

4.In this video he is touching a 200000 volt with his bare hand and he is still alive because of law ampere.My question is how he is able to control the ampere here if you can't control in the wall socket or even battery.(I thought that it has to do with ohm's law and series connection where we can divide the ampere by introducing a high resistance to the circuit.)

5.Is it safe to charge a phone with 5v and 1A rating with a power source of 5 volts and 2 A

6.In this image different currents are said to have different effects.Is it true that when I touch the AC power supply how much ampere is flowing through the body is determined by the resistance of the skin.

7.When I measured my laptop charger for AC current I was able to get about 50V(Is this because of improper earthing) but when I touched it I couldn't feel the electricity, Why is that?(I did some calculations and found that the current passing is about 0.00025 so it may be not fatal.Is this correct)

8.I heard about the electric man in India who can conduct a huge amount of electricity through his body and even turn on a grinder(LINK)and they said that he has a lot of resistance about 1.5 million ohms.My question is how does he do this(Because if he has huge resistance how does electricity even pass through his body)Can I do this trick if my skin had a very little resistance (So the current will go through my skin{My skin would behave as a super conductor})

9.why can't I use the power(P=V*I) to find out whether a human can survive an electrocution.

Thank you for all your contributions.I am so amazed by the power of stack exchange community.Any help is appreciated


closed as too broad by The Photon, Bimpelrekkie, PeterJ, R Drast, brhans Dec 12 '17 at 12:04

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • 1
    \$\begingroup\$ The rating on your phone charger is typically the maximum the charger can provide, not necessarily what is being drawn by the phone. As for your last question, it matters very much how the electricity flows through your body. It makes a difference if it goes from one side of your hand and out the other, or travels across your heart (or head). Please don't try to determine what is fatal/non-fatal by touching various electronics/wires. \$\endgroup\$ – Ron Beyer Dec 12 '17 at 6:01
  • \$\begingroup\$ Borderline case of not being a duplicate. \$\endgroup\$ – Harry Svensson Dec 12 '17 at 6:08
  • 3
    \$\begingroup\$ You should stop playing with anything electrical. \$\endgroup\$ – Solar Mike Dec 12 '17 at 6:38
  • 3
    \$\begingroup\$ Your questions are so full of wrong assumptions and misconceptions that it actually hurts my brain to read them. \$\endgroup\$ – Bimpelrekkie Dec 12 '17 at 6:51
  • 1
    \$\begingroup\$ I disagree with Solar Mike. You should START playing with (low power/low voltage) electronics! You're obviously interested but new to this. No better way to learn than the build a few simple things. Maybe start with understanding how you use a current-limiting resistor to power an LED from a 9v battery. This covers quite a few concepts above. \$\endgroup\$ – RJR Dec 12 '17 at 8:16

Actually as you asked and explain, i think you are new to electrical/electronics.

  1. Your questions make no sense to me, but every load is working on specific voltage. If you go over a specific voltage limit you can harm or burn things out. And current is dependent on voltage and load impedance, so things work fine if you work with rated voltage.

  2. Your phone charger adapter has a maximum current rating. Let's say your phone can charge at maximum of 1A. So 2000mAh battery of your phone Using 500mA adapter takes 4 hours, Using 1A adapter takes 2 hours, Using 2A adapter takes 2 hours also because your phone can handle up to 1A only. They describe current so you can charge your phone at maximum ratings.

  3. No you can't measure current with a multi-meter without load(maybe you are measuring the current by shorting it). This way you are only shorting it. Actually at the time that you short the adapter, its short-circuit protection feature shuts down the adapter for momentary time and starts it again but that time you still shorted it so it stops and starts again and again.

  4. Yes, those electrical fences have high voltage, but have little current. And such small current is not fatal. Actually this fence have high frequency and high voltage pulses. This high voltage source has more impedance than you body so this will limit the current.

  5. Yes it it safe. As i explain in 2nd answer.

  6. Yes its depend on both DC and AC current. You body not change resistance if you are electrocuted by AC or DC current. This depend on how you skin conditions is, dry or moist. But in AC current you body's parasitic capacitance(this might new for you!!) also lowers you body's impedance, so it has different effects of different frequencies.

  7. This question also makes no sense. How you can get 50V if you measure current. I don't know about your calculations but 250uA not fatal for sure.

  8. Cause you power depends on current and resistance of load.
    Power=Resistance * Current^2
    Do not change their resistance so the only property that affect power is CURRENT. This while electrocution threshold is listed in mA.


1: Am unsure of your wording. Pass.

2: 5V, 1A for your charger says that it will deliver to a 5 ohm resistor a voltage of 5V. 1A will flow through that resistor. It will likely still deliver 5V to a larger resistor load. To a load less than 5 ohms, a fuse may blow, or it will deliver less than 5V, or it will overheat....this operating area is undefined.

3:A direct current measurement with a multimeter is risky. Your multimeter may have survived. A mulitmeter set to measure current becomes a very small resistor, probably less than 5 ohm. If you want to check your charger, find a 5 ohm, 5 watt resistor, and connect it in series with your multimeter. A little less than 1A current should flow from your charger.

4: This guy is an expert. His casual approach to that high-voltage generator is deceptive. That van de graaff generator in this demo is mostly a feeble current source which helps to make it seem safer. This is a case of "don't try this at home". You can get hurt.

  • \$\begingroup\$ Re point 4 - a succinct and correct response ! nothing wrong with the others though. \$\endgroup\$ – Solar Mike Dec 12 '17 at 7:13

Not the answer you're looking for? Browse other questions tagged or ask your own question.