Chapter 44 · 910 practice MCQs
MDCAT Electrostatics MCQs 2026 | Coulomb, Fields, RC
Coulomb can push. Gravity never does. Unit 8 is , E as force per unit charge, field lines, and RC — and the midpoint of two pluses that is not ‘twice the field’.
·6 min read·Usman Ubaid
What MDCAT 2026 asks in Unit 44 Electrostatics
PMDC Unit 8 is electrostatics plus the RC circuit that sits at the end of the chapter. Coulomb’s law is 1/r², like gravity but able to repel. The field E is F on a unit positive test charge. Field lines start on + and end on −; they never cross; density is the strength.
Potential falls as 1/r, not 1/r². Superposition is a vector sum for E and an algebraic sum for V. A conducting plate has outside; a non-conducting sheet is /2 ₀ — mixing those two is a whole option.
RC: charging ), discharging . At you still have 37% on a discharge, not zero. Twenty labs, from two point charges to a charging curve.
- , along the line joining, attract unlike, repel like.
- Midpoint of two equal pluses: Midpoint of + and −: the fields add toward the negative.
- V is work per unit charge from infinity. Scalars add.
- Conducting plate non-conducting sheet
- = RC. Charge 63% of the way to the new value in one time constant.
Often-asked Electrostatics MCQ patterns
These are the Electrostatics ideas that keep coming every year with new numbers.
- Using 1/r for force or 1/r² for potential — swapped exponents.
- Adding E as scalars at a midpoint of two pluses.
- Confusing 0.37 (discharge at with 0.63 (charge gained while charging).
Worked Electrostatics numericals (
Work these on paper first. Then open the Unit 44 quiz — the same numbers are in the questions, with wrong options built from the usual mix-ups.
Equal positive charges at A and B. Electric field at the midpoint?
- Each E points away from its source. At the midpoint they are equal and opposite.
- Vector sum is zero. Potential, a scalar, is not zero — it is 2kq/r.
, V ≠ 0. Field is a vector; potential is not.
A capacitor charged to discharges through R. Charge at
- 0.63 is how much has left (or how much a charging capacitor has gained).
About 37% remains. One time constant is not ‘empty’.
Electrostatics traps that steal the mark
A good option is a true sentence about the wrong quantity. If you miss, the quiz names the mix-up on the option you actually picked.
- Using 1/r for force.
- Adding E as scalars at a midpoint of two pluses.
- Confusing 0.37 with 0.63 .
- Using /2 ₀ for a conducting plate (that is the sheet).
- Saying field lines cross where the field is ‘strong’.
Electrostatics formula sheet for MDCAT 2026
Write these until they are cheaper than thinking. Then open the Electrostatics quiz and make the picture agree.
How to practise Unit 44 Electrostatics MCQs
On every two-charge stem, draw the two E arrows before you add. Then ask whether the question wanted E or V — they disagree at a midpoint of two pluses.
On RC, write ‘charging’ or ‘discharging’ at the top of the working. The formulae look similar; the graphs do not.
Sit Electrostatics before Current Electricity. RC is the bridge.
Choose topics and a test length up to 180 from the 910-question bank. Tutor Mode explains each selection; Timed Exam reveals explanations on submission. Use the complete review to revise mistakes and download your results.
FAQ
Common questions
Are RC circuits in the MDCAT electrostatics chapter here?
Yes — charging and discharging sit at the end of Unit 8, after Coulomb, fields, lines and potential.
Why is the midpoint field of two equal pluses zero?
The two E arrows are equal and opposite. Superposition is a vector sum, not a pile of magnitudes. Potential is a scalar and adds rather than cancelling like opposite field vectors. Two equal positive charges can therefore give zero electric field at the midpoint while their potential remains positive.
What is the RC time constant in MDCAT?
= RC. In one a discharging capacitor falls to about 37% ; a charging one rises to about 63% of . After one time constant the exponential factor is e⁻¹ ≈ 0.368. RC has units of seconds; increasing either resistance or capacitance makes charging and discharging slower.
E vs V — which falls faster with distance?
E ~ 1/r², V ~ 1/r for a point charge. Mixing the exponents is the standard miss. Doubling distance from a point charge reduces field magnitude to one quarter and potential to one half. These distance laws apply to a point charge or the external field of a spherically symmetric charge distribution.
Conducting plate or infinite sheet — which E is ₀?
The conducting plate (or the surface of a conductor). A non-conducting infinite sheet is /2 ₀.
How many Electrostatics MCQs are available on DIFF. MDCAT?
The current Electrostatics question bank contains 910 practice MCQs across 4 topics. This is the bank size, not the length of one test. Choose your topics and a question count from 1 to 180, limited by the questions available in those topics.
Which topics does the Electrostatics quiz cover?
The selectable topics are Coulomb's Law, Electric Field, Electric Potential, Capacitors. Use Select all for a broad chapter drill, Clear to start a focused selection, or choose individual topics. Questions are drawn from your chosen topics, so you can target a weak concept before returning to a wider test.
How do I build a custom Electrostatics test?
Open the chapter builder, select one or more topics, enter your question count, and choose Tutor Mode or Timed Exam. The available-question total updates with your selection. Start Test generates a shuffled drill; you do not have to follow a fixed Quiz 1 or Quiz 2 sequence.
What is the difference between Tutor Mode and Timed Exam?
Tutor Mode gives feedback and an explanation after you choose an option, and you can change or clear that choice. Timed Exam runs a countdown and keeps explanations hidden until submission. Both modes let you move between questions, use the paper map, and submit for a complete review.
How do I review and download my Electrostatics quiz?
Select Submit Quiz, then Submit & View Explanations. The review includes every question in your test, all options, your selection, the marked correct answer when a key is available, and the explanation. Download PDF saves a paginated review; Download Review saves an HTML copy you can open in a browser. The review also includes DIFF. MDCAT community links.
How should I use Electrostatics MCQs to improve?
Start with a short tutor drill on one of these topics: Coulomb's Law, Electric Field, Electric Potential. Read the explanation for incorrect and uncertain answers, revise the relevant textbook section, and retry before taking a timed drill. Compare your reasoning with the answer key rather than memorising the option letter.
Ready to sit Unit 44 Electrostatics — 910 MCQs, 910 labs?