Verification of OHM’s law By: Engr.Irshad Rahim Memon

 Objective of this practical is to verify that voltage applied to a closed resistive path is equal to the product of current flowing through and resistance of that path

 Few resistors  bread board  multimeter  variable DC power supply  connecting wires etc

 Ohm’s law states that current through a closed resistive path is directly proportional to applied voltage, where resistance of path is kept constant.  Ohm experimentally determined that if the voltage across resistor is increased, current through resistor will also increase as shown in figure 01.

Figure 01: Ohm law for constant resistance (a) less voltage, less current (b) more voltage, more current

 Ohm also determined if voltage is kept constant then less resistance results in more current and more resistance results in less current as shown in figure 02

 Figure 02: Ohm law for constant voltage (a) less resistance, more current (b) more resistance, less current

 Ohm also determined if voltage is kept constant then less resistance results in more current and more resistance results in less current as shown in figure 02.

 Ohm’s law can be formulated as follows:

 Connect a variable voltage source, a resistor and an ammeter in series as shown in figure 03(a) to verify direct relationship between voltage and current as shown in figure 03(c)

 Verification of Ohm’s law for constant resistance (a) circuit (b) different values of current for different values of voltage (c) graphical relation between voltage and current

 Also connect a variable resistor, a voltage source and an ammeter in series as shown in figure 04(a) to verify inverse relationship between resistance and current as shown in figure 04(c)

 It is observed that current varies directly with applied voltage where resistance is kept constant. It is also observed that current varies inversely with resistance where applied voltage is kept constant.

 Fill the missing quantity in the table 01 with the help of Ohm’s law. S.No R (Ohm) I (Ampere) V (volt) Example1K22K 15M m1

Verification of Kirchhoff’s Voltage Law (KVL) By: Engr.Irshad Rahim Memon

 Objective of this practical is to verify KVL.

 Few resistors  bread board  multimeter  variable DC power supply  connecting wires etc

 Kirchhoff’s voltage law states that “sum of all the voltage drops around a single closed path in a circuit is equal to the total source voltage in that loop” or it can also be defined as “The algebraic sum of all the voltages (both source and drop) around a single closed path is equal to zero” as shown in figure 01.

 Figure 01: Demonstration of KVL

 KVL may be formulated as follows. Vs=V1+V2+V3+…+Vn or Vs-V1-V2-V3-…-Vn=0

 For the verification of KVL, a simple series resistive circuit like shown in figure 01 should be prepared.

 KVL is verified  KVL law is verified for series circuit of three resistors of known values connected in series. Results are given in table 01.

S.No Vs V R1 V R2 V R3 V s= V R1 +V R2 +V R3 example10Volt2 Volt3 Volt5 Volt10 Volt=2+3+5 Volt 15Volt 215volt 320volt

Verification of Kirchhoff’s Current Law (KCL) By: Engr.Irshad Rahim Memon

 Objective of this practical is to verify KCL.

 Few resistors  bread board  multimeter  variable DC power supply  connecting wires etc

 Kirchhoff’s current law states that “Algebraic sum of all currents entering and leaving a node is equal to zero” as demonstrated in figure 01.

 Figure 01: Demonstration of KCL

 For the verification of KCL, a simple parallel resistive circuit like shown in figure 02 should be prepared.

 Figure 02: Verification of KCL

 KCL law is verified for parallel circuit of three resistors of known values connected in parallel. Results are given in table 01.

S.No I total I R1 I R2 I R3 I total = I R1 +I R2 +I R3 example1Amp1Amp0.5 Amp0.3 Amp0.2 Amp1Amp= Amp 10.5 Amp Amp0.25 Amp 30.1 Amp