Tag: Potentiometer diagram drawing Smarter techniques physics

 

“How to Draw Circuit Diagrams in Physics (HSC Level) – Smart Techniques with Step-by-Step Guide”

Author:
Prof. Kali C. S.
M.Sc., M.Ed., D.C.S.
50+ Years of Experience in Physics Teaching

1. Introduction:

        Many students can solve numerical in electricity but hesitate when the question is, “Draw the circuit diagram for this experiment.” Circuit symbols, series–parallel connections and crowded practical setups make the diagram look difficult.  This post shows a simple, step-by-step method to understand each instrument first and then combine them into neat, examination ready circuit diagrams for your class 11–12 electricity experiments.

2. Why start from symbols?

     Before drawing a big circuit like Whetstone’s bridge or a potentiometer, it is essential to know the basic electrical components and their standard symbols used in textbooks and board examinations. Once these 10–12 symbols are familiar, any practical circuit becomes just a meaningful arrangement of these small bricks rather than a scary picture. You may introduce this section with a sentence such as:
“First learn the language of circuit diagrams – the symbols – and then learn to write sentences with them – the full experiment circuits.”

3. Essential components up to HSC level:

Here is a compact description:

 3.1.  Cell / Battery
Source of emf for the circuit, always drawn with + and – terminals clearly shown. A single cell has one long and one short line; a battery is a group of such cells in series.

 3.2. Ammeter (DC)
Measures current in the circuit. It is always connected in series with the branch whose current you want to measure and must have its + terminal towards the higher potential side.

 3.3. Voltmeter (DC)
Measures potential difference between two points. It is always connected in parallel across the component (resistor, wire segment, cell, etc.) and again has + and – terminals marked.

 3.4. Galvanometer
Sensitive device to detect small current. It is connected in series in a branch where you want to check “current or no current”, as in Whetstone’s bridge or potentiometer balancing.

 3.5. Key / Switch
Simple on–off device. Drawn in series with the battery so that the whole circuit can be made live or dead by opening/closing the key.

 3.6. Resistor

     Resistor provides fixed resistance; rheostat gives variable resistance to control current.

 3.7. Rheostat
A rheostat is always in series with the circuit (or the relevant branch) and is drawn with an arrow indicating the moving contact.

 3.8. Connecting Wire Wires join components.

 3.9. Metal Strip
Metal strips represent brass or copper strips on experiment boards, often drawn as straight segments with endpoints used to connect other parts of the circuit. ​

 3.10. Earth (Ground) Earth symbol indicates a connection to ground.

 3.11. Diode

     A diode symbol shows a unidirectional device, used when you discuss rectifiers or protection circuits. Your original Table A can be retained but polished into a clean table (Name – Symbol – Use – Series/Parallel – Remark) so that students can revise quickly before the practical exam

  3.12. AC generator

          An AC generator (alternator) is a device that converts mechanical energy into electrical energy in the form of alternating current using electromagnetic induction.

3.13.   Load

       The load is the part of the circuit that consumes electrical power, such as a lamp, resistor, motor or any appliance connected across the source.

  4.  Table  A   gives the list of  instruments involved up to H. S. C. level with name, electric symbol, use, series/ parallel connection and remark  about each instrument.

Table A

No.	Instrument	Electric Symbol	Use	Series/Parallel	Remark
1	Cell		Source	Series	+ , – terminals
2	Battery		Source	Series	+ , – terminals
3	Ammeter D.C.		Current measurement	Series	+ , – terminals
4	Voltmeter D.C.		Voltage measurement	Parallel	+ , – terminals
5	Galvanometer		Current detection	Series
6	Key		On-Off  switch	Series
7	Resistor		To control Current	Series/Parallel	Fixed resistance
8	Rheostat		To vary current	Series	Variable Resistance
9	Wire		Circuit Connection	Series/Parallel
10	Metal strip		Part of Instrument	Series/Parallel
11	Ground		Earthing	Series/Parallel
12	Diode		Unidirectional Device	Series/Parallel
13	AC generator		converts mechanical energy into electrical energy	Series/Parallel
14	Load		consumes electrical power	Series/Parallel

  5. Standard source block (Fig A):

Fig.A

 

5.1 Why Use a Standard Block?

  To avoid redrawing battery, key and rheostat every time in a different style, fix a standard “source block” for all electricity experiments.

5.2 How to draw it

• Draw a neat rectangle or group of symbols containing: battery, key and rheostat in series.
• Mark its two terminals as A and B. These are the points where the rest of the experimental circuit will be attached. Below this figure, note: “This set acts as the common electric source for all HSC level electricity experiments.”

Once students remember this block, each experiment reduces to: “Attach the suitable arrangement of resistances, wire and galvanometer between A and B.”

6. Wheatstone bridge – idea and circuit:

  6.1. Aim of the circuit

     In a Wheatstone bridge, four resistances are arranged in the form of a bridge to compare an unknown resistance with known ones using the condition of null deflection in a galvanometer.

  6.2. Logical layout

    Tell students to imagine a rectangle of four resistors: left arm R, right arm X (unknown), and the top and bottom arms made of known resistances or strips with a 1 m wire between A and B. The galvanometer forms the “bridge” between the midpoints of the two vertical arms.

  6.3. Step-by-step drawing:

Fig. B

      1.  Draw two L‑shaped metal strips at the left and right margins of the page, and a straight strip between them to represent the wooden board. Join the top ends of the two strips by a straight line; this will be the 1 m wire AB used for balancing.

 2. Mark its ends clearly as A and B. At the bottom of the left strip draw the known resistance R and at the bottom of the right strip draw the unknown resistance X in series between A and B, forming the four arm bridge.

 3. From the midpoint of the left strip draw a line to the galvanometer symbol, and from the other terminal of the galvanometer draw a line to a sliding contact (jockey) touching the wire at some point C on AB.

 4. Attach the standard source block (battery + key + rheostat) between A and B using your fixed symbol set, keeping polarity consistent.

 5. Label the segments AC = lᵣ and CB = lₓ if you want to connect the diagram visually with the formula

 6. X=R.l_x/l_r

 7. “This completes the neat circuit diagram of Wheatstone’s bridge used to determine an unknown resistance by the null‑deflection method

7. Potentiometer – idea and circuit:

  7.1. Aim of the circuit

    In a potentiometer, a long uniform wire is used to compare emf of two cells or to find internal resistance by balancing potential differences without drawing current from the cell being measured.

  7.2. Logical layout

     Visually, the potentiometer board is shown as a long set of wires divided into equal segments, with end terminals A and B. The main battery with rheostat is connected across A and B, and the secondary circuit (cell + galvanometer + jockey) is attached along the length to find the balancing length.

 7.3. Step-by-step drawing:

Fig. C

  1. In the middle of the page, draw four long, straight, parallel strips and join their ends so they look like one continuous multi segment wire. Mark the left end as A and the right end as B; this is the potentiometer wire, total length usually 4 or 10 m in the real apparatus.

  2. Between A and B, below the wire, place the standard source block: battery, key, and rheostat in series. Make sure the positive terminal of this battery is connected to A. On one side, draw a second small cell whose emf is to be compared or measured.

 3. Connect its positive terminal to A and its negative terminal to a galvanometer. From the other terminal of the galvanometer, draw a line to the jockey symbol touching the potentiometer wire at some point C, which represents the balancing point.

 4. Indicate the balancing length AC = L₁(for first cell) and AC = L₂(for second cell) if two cells are used, and write the emf relation below the diagram, for example

  5. E₁/E₂ =L₁/L₂

  6. Close this section with:
“This gives the standard circuit diagram of a potentiometer used for comparison of emfs or measurement of internal resistance in the class 12 practical.”

  8. Why this method works (The Psychology behind it)

This technique is effective because:

 ✔ You draw using shapes, not memory

L-shapes, rectangles, and straight lines create a clear visual structure.

 ✔ You add instruments only after the structure is ready

No confusion about placement.

 ✔ You always begin from A & B

Consistent orientation makes every diagram uniform.

 ✔ You understand the role of each component

Instead of copying, you logically place each part.

 ✔ Your final diagram looks clean, professional, and exam-ready

  9. Common mistakes students make (and how to avoid them)

  1. Drawing voltmeter in series (should be parallel)

  2. Ammeter drawn without observing polarity

  3. Galvanometer wrongly connected to battery

  4. Jockey drawn at the wrong position

  5.  Main supply connected across wrong terminals

  6. Potentiometer wire drawn too short or too long

   7. No separation between primary and secondary circuits

   8. Symbols drawn incorrectly (especially diode, rheostat)

  9. Follow the step wise technique and these errors disappear.

 10. Conclusion:

 1. Learning to draw circuit diagrams is not about memorizing textbook figures.

  2. It is about understanding the structure, symbols, and sequence.

 3. Using the “Smarter Techniques” method:

 4.  You begin with simple lines and shapes

 5. Add only the essential components

 6.  Complete the diagram with clean, logical connections

 7. With practice, you will be able to draw any electricity experiment diagram quickly and confidently.

  

11. Video support:

To see the actual drawing process in action, refer to the demonstration in the following video:

YouTube Video: How to Draw Circuit Diagrams for Electricity Experiments?