# how to find out current through inductor in DC circuit?

Joined Nov 24, 2011
629
Hello
I need help to understand the basic concepts of inductor. Suppose 1h inductor is connected across 10v battery. Inductor is non linear element it change the value of current over the time. How to find out current through inductor?

#### Ramussons

Joined May 3, 2013
890
Any problem using a Ammeter or Millammeter? #### Kermit2

Joined Feb 5, 2010
4,162

Joined Nov 24, 2011
629
Any problem using a Ammeter or Millammeter? I can use the multimeter but I just want to find out using the formula.

#### Alec_t

Joined Sep 17, 2013
11,749
E=10, L=1. Use the formula to find di/dt.

Joined Nov 24, 2011
629
I looked that link, that is the calculation for the RL circuit. In my circuit the single inductor is connected across the DC source. I am looking the formula so that I can find out the current through inductor

#### DickCappels

Joined Aug 21, 2008
6,655
You can use the formula for LR circuits. Use an ohmmeter to find the resistance of your inductor and use that value as R in the formula.

Joined Nov 24, 2011
629
E=10, L=1. Use the formula to find di/dt.
So I don't know time and I have find out the current. Should I have to suppose the time

#### DGElder

Joined Apr 3, 2016
351
The current will rise linearlly at 10A per second, until the universe explodes. At least that is what would happen if you had ideal inductor and voltage source. Real components have resistance, use the tutorial math. You will need to know the source output resistance and inductor resistance to calculate the current.

Don't try hooking that up, you will pop a fuse or drain your battery.

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#### Alec_t

Joined Sep 17, 2013
11,749
I have find out the current. Should I have to suppose the time
di/dt means 'the rate of change of current with time'. If you found one (non-zero) value of the current that must have been at one specific time, unless the current had reached a value limited by the resistance of the inductor.

• Joined Nov 24, 2011
629
di/dt means 'the rate of change of current with time'. If you found one (non-zero) value of the current that must have been at one specific time, unless the current had reached a value limited by the resistance of the inductor.
given
V=10v, L=1h, di/dt=10A/s
Voltage drop across the inductor is
v=Ldi/dt
v=1*10=10v
Voltage drop across the 1h inductor is 10 volt
Still the current is unknown

#### crutschow

Joined Mar 14, 2008
25,675
If you can't understand what is being said to you then how can we help? The current isn't unknow, you just haven't calculated it.
The current in an inductor continually increases with time after the application of a DC voltage according to (di = Vdt/ L).
This gives the increase in current with time.
To find the current at any point in time you multiple the time by V/L
Thus, in you example, at 5 seconds the current would be 5s * 10A/s = 50A
The maximum current in the inductor after a large period of time is limited by any resistance in the circuit and will settle at a value of V / R.

If you can't understand that, than I don't know what further can be said. • Joined Nov 24, 2011
629
Now I can understand and I can find out the energy stored in inductor
E=1/2Li*i
E=0.5*1*50*50
E=1250 joules

Power P=Li*di/dt
P=1*50*10
P=500W
Is this calculation is correct?

#### Papabravo

Joined Feb 24, 2006
14,691
Now I can understand and I can find out the energy stored in inductor
E=1/2Li*i
E=0.5*1*50*50
E=1250 joules

Power P=Li*di/dt
P=1*50*10
P=500W
Is this calculation is correct?
That equation is not true when V and i have reached their steady state values. As you know, steady state means nothing is changing, and so di/dt will be zero for all future time and the value of L will be irrelevant, thus:

$$P_L\;=\;i^{2} \times R_L\;=\;\left(\frac{V_L}{R_L} \right) ^2\times R_L$$

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• Joined Nov 24, 2011
629
Now I just connected the AC supply across 1h inductor
If the applied voltage is 10v AC with 60Hz signal than I am trying to find out current through inductor
Inductive reactance XL=2*3.14*f*L
XL=2*3.14*60*1
XL=377.11ohms
Now I know the Inductive reactance than I can calculate current through indctor
I=V/XL=10/377.1=0.0265A
I just wanted to know that how can we determine current through the inductor in AC and DC circuit
So again, please check my work and if there is any mistake tell me

#### DGElder

Joined Apr 3, 2016
351

#### WBahn

Joined Mar 31, 2012
26,305
Hello
I need help to understand the basic concepts of inductor. Suppose 1h inductor is connected across 10v battery. Inductor is non linear element it change the value of current over the time. How to find out current through inductor?
An inductor is NOT non-linear element.

What is your math background like? Have you seen any calculus yet? Do you understand exponentials and logarithms?

Joined Nov 24, 2011
629
Power in AC circuit
P=i*i*XL
P=0.265*0.265*377.11
P=0.2648w
How to calculate energy in AC circuit

#### WBahn

Joined Mar 31, 2012
26,305
Power in AC circuit
P=i*i*XL
P=0.265*0.265*377.11
P=0.2648w
How to calculate energy in AC circuit
What energy are you trying to calculate? There are different energy questions that could be asked.