Types of Banks and Banking Structure

Indian banks are broadly classified as Scheduled and Non-Scheduled. Scheduled banks are listed in the 2nd Schedule of the RBI Act, 1934, and include: Commercial Banks (Public Sector, Private Sector, Foreign, Regional Rural Banks) and Cooperative Banks. Public Sector Banks (PSBs) are majority government-owned; SBI is the largest. After mergers (2020), India has 12 PSBs. Private banks include HDFC, ICICI, Axis. Regional Rural Banks (RRBs) were set up in 1975 (Narasimham Committee) to serve rural areas — jointly owned by Central Govt (50%), Sponsor Bank (35%), State Govt (15%). Memory aid for RRB ownership: '50-35-15'. NABARD is the apex body regulating RRBs and cooperative banks.

Every charger in your house, every laptop adaptor, every NEET-relevant power supply hides the same trick: a diode-based circuit that turns alternating current into direct current. Rectifiers are where the abstract pn-junction you studied meets a real electronic device, and NEET asks about them every single year.

Definition: A rectifier is a circuit that converts alternating current (AC) into pulsating direct current (DC) by exploiting the diode's property of conducting only when forward biased.

Definition: Half-wave rectification is the process in which only one half-cycle of the input AC appears at the output; the other half is blocked.

Definition: Full-wave rectification is the process in which both half-cycles of the input AC are made to drive current through the load in the same direction.

The starting point — the diode's one-way street

A pn-junction diode conducts when its anode is more positive than its cathode (forward bias) and blocks current when the polarity is reversed (reverse bias). The forward voltage drop across a silicon diode is roughly 0.7 V; for germanium it is about 0.3 V. NEET problems usually assume an ideal diode, so this drop is ignored unless the question states otherwise.

When you apply a sinusoidal AC voltage V = V₀ sin(ωt) across a diode, the diode conducts during the positive half of every cycle (when V > 0) and blocks during the negative half. That selective conduction is rectification. The rest of the chapter is just about how cleverly you arrange diodes to keep more of the input.

Half-wave rectification

In a half-wave rectifier, a single diode is placed in series with the load (typically a resistor R_L). The transformer steps the mains AC down to the desired secondary voltage, and the diode-resistor combination delivers the output.

• During the positive half-cycle, the diode is forward biased and conducts, so current flows through R_L and a positive voltage appears across it.
• During the negative half-cycle, the diode is reverse biased and acts as an open switch; no current flows and the voltage across R_L is zero.

The output waveform is a series of positive humps separated by gaps — half a sine wave repeating at the same frequency as the input.

Key numerical results to memorise for NEET:

• Output frequency = f (same as input frequency, because we drop every alternate half-cycle).
• Peak Inverse Voltage (PIV) across the diode = V₀ — the diode must withstand the full peak of the source while reverse biased.
• Average (DC) output voltage = V₀ / π.
• RMS output voltage = V₀ / 2.
• Rectifier efficiency ≈ 40.6% (theoretical maximum, assuming an ideal diode).
• Ripple factor ≈ 1.21 — very high, so a half-wave rectifier produces noisy DC.

The ripple factor measures how much AC content survives in the output; a higher ripple means a worse rectifier, and 1.21 means more than 100% AC content riding on the DC.

Full-wave rectification

The half-wave design throws away half the energy. A full-wave rectifier flips the negative half-cycle of the input into a positive half-cycle at the load, so current always flows in the same direction through R_L. Two practical configurations exist.

Centre-tap full-wave rectifier

A transformer with a centre-tapped secondary feeds two diodes whose cathodes are tied together at the load. During the positive half-cycle of the secondary, one diode is forward biased and conducts. During the negative half-cycle, the second diode is forward biased and conducts. The current through R_L flows in the same direction in both halves.

• Two diodes are used.
• PIV across each diode = 2V₀ (a non-conducting diode sees the full peak-to-peak secondary voltage).
• The transformer needs a centre tap, which complicates winding.

Bridge rectifier

Four diodes arranged in a diamond around the load. The diodes pair off such that two conduct during each half-cycle. The bridge needs no centre tap, so it uses the full secondary voltage on each half-cycle, and PIV per diode is only V₀.

• Four diodes, no centre tap, full secondary voltage utilised.
• PIV across each diode = V₀, the same as in a half-wave rectifier.
• This is the configuration in almost every modern phone charger and DC power supply.

Either way, the full-wave output is twice as dense in time as the half-wave output:

• Output frequency = 2f (every input half-cycle produces an output hump).
• Average (DC) output voltage = 2V₀ / π.
• RMS output voltage = V₀ / √2.
• Rectifier efficiency ≈ 81.2% — twice that of half-wave.
• Ripple factor ≈ 0.48 — much lower than 1.21, so the output is far smoother.

The filter — turning humps into flat DC

Both rectifiers produce pulsating DC, not steady DC. To smooth this out, a capacitor filter is placed across the load. The capacitor charges to the peak during each rising portion of the hump and discharges slowly into the load during each falling portion, filling in the gaps and giving an output that looks like a slightly wavy line near V₀.

In a full-wave rectifier the capacitor only has to bridge a half-period gap (T/2), whereas in a half-wave rectifier it must bridge a full-period gap (T). That is why full-wave rectifiers need smaller capacitors for the same ripple — another practical edge.

Why it matters

Why it matters: NEET-UG reliably asks at least one Electronic Devices question on rectifier output frequency, PIV or efficiency, and JEE-Main mirrors the trend. The topic also forms the conceptual bridge into the next chapter — special-purpose diodes such as the Zener diode for voltage regulation. Beyond exams, every USB charger and laptop adapter starts its life as a bridge rectifier. The same physics powers solar inverters in millions of Indian homes.

Real-world example

Real-world example: Open any mobile phone charger and you will find a small bridge rectifier on the input side — four tiny diodes (sometimes packaged as a single chip) converting 230 V AC from the mains into pulsating DC. A capacitor across them flattens the ripples; a switching regulator then steps the result down to 5 V. Every time you plug in your phone, your half-wave-versus-full-wave knowledge is at work.

Common misconception

Common misconception: Students often write that "full-wave rectifiers double the input voltage." They do not. They double the output frequency and roughly double the efficiency; the peak output voltage is still essentially V₀ (minus the diode drop). Read the question carefully — frequency and voltage are different quantities.

A second misconception is that a capacitor filter "produces pure DC". It only reduces the ripple. The output still has small fluctuations called the ripple voltage; this is why critical electronics use additional regulator ICs after the capacitor filter.

A third trap is the PIV of a centre-tap rectifier. Many candidates write V₀, forgetting that the non-conducting diode sees both the full positive peak of one half of the secondary and the cathode pinned to the conducting diode's positive output — totalling 2V₀.

Quick classification practice. SBI — Public Sector Commercial Bank. HDFC Bank — Private Sector Commercial Bank. Citibank India — Foreign Bank. Prathama Bank — Regional Rural Bank. India Post Payments Bank — Payments Bank. AU Small Finance Bank — Small Finance Bank. Saraswat Bank — Urban Cooperative Bank. For exam speed: if a name contains 'Payments Bank' or 'Small Finance Bank', the type is explicit. RRBs usually carry regional/local names (e.g., Baroda Rajasthan Kshetriya Gramin Bank). Cooperative banks often have 'Cooperative' or community names. Foreign banks (Citi, HSBC, Standard Chartered, DBS) operate branches in India but are headquartered abroad.

Cover the answer, recall, then check. 12 cards on the structure of Indian banking for IBPS Clerk.

Q1. What is a scheduled bank?
A1. A bank listed in the Second Schedule of the RBI Act, 1934. It gets RBI borrowing facilities but must maintain CRR and be a member of the clearing house.

Q2. Name the four types of scheduled commercial banks.
A2. Public Sector Banks, Private Sector Banks, Foreign Banks, and Regional Rural Banks (RRBs).

Q3. How many public sector banks exist after the 2020 mega-mergers?
A3. 12 public sector banks. SBI is the largest bank in India.

Q4. What are payment banks allowed and not allowed to do?
A4. They accept demand deposits (up to ₹2 lakh per customer) and offer remittances/cards, but CANNOT lend or issue credit cards.

Q5. What is the key mandate of Small Finance Banks (SFBs)?
A5. Financial inclusion — they must extend 75% of lending to priority sectors and can do full banking (accept deposits and lend).

Q6. Under which Act were RRBs set up, and which was the first RRB?
A6. The RRB Act, 1976 (on the Narasimham Working Group's recommendation). First RRB: Prathama Bank (2 Oct 1975), sponsored by Syndicate Bank.

Q7. Who are the three shareholders of an RRB and in what ratio?
A7. Central Government (50%), Sponsor Bank (35%), State Government (15%).

Q8. What is a cooperative bank?
A8. A bank run on cooperative (member-owned) principles; regulated jointly by RBI and Registrar of Cooperative Societies (dual control), later strengthened under RBI.

Q9. Differentiate the money market's "banker" role: what is a Universal Bank?
A9. A bank offering a wide range of services — retail, wholesale, investment banking — under one roof.

Q10. Which committee recommended payment banks and SFBs?
A10. The Nachiket Mor Committee (2013–14) on Comprehensive Financial Services.

Q11. What are NBFCs and how do they differ from banks?
A11. Non-Banking Financial Companies lend and invest but cannot accept demand (chequable) deposits and are not part of the payment/settlement system.

Q12. What distinguishes a non-scheduled bank?
A12. It is NOT in the Second Schedule of the RBI Act; it keeps reserves with itself and cannot normally borrow from the RBI except in emergencies.

Indian banking has a clear pyramid with the RBI at the apex. In IBPS Clerk, "Banking Awareness" is the heart of the GA section, and questions on types of banks are near-certain. Knowing the structure lets you answer 2–4 questions almost every year with pure recall.

The core idea

The first split is scheduled vs non-scheduled banks. A scheduled bank is listed in the Second Schedule of the RBI Act, 1934; it can borrow from the RBI and must maintain CRR. Scheduled commercial banks then divide into Public Sector Banks, Private Sector Banks, Foreign Banks and Regional Rural Banks (RRBs), alongside Cooperative Banks.

Newer "differentiated" banks were created for inclusion: Payment Banks (accept deposits up to ₹2 lakh, no lending, no credit cards) and Small Finance Banks (full banking, but 75% of loans to priority sectors) — both from the Nachiket Mor Committee's ideas.

Must-know durable facts

Type	Key point
Public Sector Banks	12 after 2020 mergers; SBI is largest
RRBs	RRB Act 1976; first = Prathama Bank (1975)
RRB shareholding	Centre 50% : Sponsor Bank 35% : State 15%
Payment Banks	Deposits ≤ ₹2 lakh; cannot lend
Small Finance Banks	75% lending to priority sector
Cooperative Banks	Dual control (RBI + Registrar)

Exam Tricks & Tips

• 🎯 Mnemonic "PIP-CFR" for scheduled commercial banks: Public, Private, Foreign, RRB (plus cooperatives).
• 🎯 Payment banks = "Pay, don't Lend" — remember they move money but never give loans.
• 🎯 RRB shareholding 50-35-15 — Centre highest, State lowest.
• 🎯 "Second Schedule" is the magic phrase — if a question says a bank borrows from RBI/keeps CRR, it is scheduled.
• 🎯 SFB = Serves the Small — 75% priority-sector lending.
• ❌ Common mistake: thinking payment banks can issue credit cards or loans — they can issue only debit/ATM cards.

Expected exam pattern

One-liner recall: "First RRB was ___", "Payment bank deposit limit is ___", "How many PSBs after merger?" Occasionally a match-the-column of bank type to feature.

Quick recap

RBI at the top; scheduled banks are in the Second Schedule; commercial banks = Public/Private/Foreign/RRB; payment banks accept deposits but never lend; SFBs do 75% priority lending; RRB ownership is 50-35-15.