UPHESC Assistant Professor Physics 2025 PYQs

Concept: Check each statement.

1. a – correct: the Ganga basin is India's largest (about a quarter of the country's area).
2. b – correct: the Bhagirathi rises at Gaumukh (Gangotri glacier) in Uttarkashi district, Uttarakhand.
3. c – wrong: Satluj and Jhelum belong to the Indus system.
4. d – correct: the Son is the main right-bank tributary (others: Yamuna, Tons… ).

Short trick: Punjab rivers (Jhelum, Chenab, Ravi, Beas, Satluj) → Indus; drop c.

Concept: The Khyber Pass, in the Spin Ghar (Safed Koh) range, is in Khyber Pakhtunkhwa, Pakistan.

1. It links Peshawar (Pakistan) with Jalalabad/Kabul (Afghanistan) via Torkham border.
2. It was the historic invasion and trade route into the Indian subcontinent.

Short trick: Khyber → Khyber Pakhtunkhwa → Pakistan.

Concept: The Coriolis effect is the apparent deflection of moving objects caused by the Earth's rotation.

1. Deflection is to the right in the Northern Hemisphere and to the left in the Southern; it is zero at the equator and maximum at the poles.
2. Pressure differences drive winds, and the Coriolis effect deflects them; ocean currents are deflected by it, not its cause; the Moon causes tides.

Short trick: Rotation → Coriolis; Moon → tides.

Concept: Kirsty Coventry, a Zimbabwean former swimmer, was elected IOC President on 20 March 2025 (Costa Navarino, Greece).

1. She is the 10th IOC President, the first woman and the first African; she succeeded Thomas Bach (Germany) in June 2025.
2. She won 7 Olympic medals, including 200 m backstroke gold in 2004 and 2008, and was Zimbabwe's sports minister.

Short trick: First woman + first African IOC chief = Coventry of Zimbabwe.

Concept: NPP 2000 has immediate (unmet contraception needs), medium-term (TFR to replacement level 2.1 by 2010) and long-term objectives.

1. Long-term objective: a stable population by 2045, consistent with economic growth and environment protection → 1 correct.
2. National socio-demographic goals include reducing MMR to below 100 per 100,000 live births (and IMR below 30 per 1000) → 2 correct.

Short trick: NPP 2000: TFR 2.1 by 2010, stable population by 2045, MMR < 100, IMR < 30.

Concept: The capital market deals in long-term funds – equity and debt; the best-known capital markets are the stock market and the bond markets.

1. Stock (share) market → equity capital; bond market → long-term debt capital.
2. A depository account (with NSDL/CDSL) only holds securities in electronic (demat) form – it is a facility, not a market.

Short trick: Capital market = shares + bonds; demat = locker, not market.

Concept: FICCI (Federation of Indian Chambers of Commerce and Industry) was founded in 1927 on the advice of Mahatma Gandhi by G. D. Birla and Purshottamdas Thakurdas.

1. It is India's oldest and largest apex business organisation, headquartered in New Delhi.
2. Gandhi only advised; J. R. D. Tata was a co-author of the 1944 Bombay Plan with them, not a FICCI founder.

Short trick: FICCI 1927 = Birla + Thakurdas (Gandhi's advice).

Concept: Right to Equality = Articles 14–18 of the Constitution (the English List-II gives Articles; the Hindi version prints 'अनुसूची' (Schedule), but the numbers 14–17 can only be Articles – the Constitution has just 12 Schedules).

1. Art 14 – equality before law and equal protection of laws → a-I.
2. Art 15 – no discrimination on grounds of religion, race, caste, sex or place of birth → b-II.
3. Art 16 – equality of opportunity in public employment → c-III.
4. Art 17 – abolition of untouchability → d-IV (Art 18 – abolition of titles).

Short trick: The rights follow the article order 14-15-16-17 → straight I-II-III-IV.

Concept: Article 81 caps the Lok Sabha at 530 members from the States + 20 from the Union Territories = 550.

1. Earlier, Article 331 allowed the President to nominate 2 Anglo-Indians, which made the maximum 552.
2. The 104th Amendment (2019, effective 25 Jan 2020) ended Anglo-Indian nomination, so the maximum now fixed by the Constitution is 550.
3. 545 was the actual strength (543 elected + 2 nominated) up to the 16th Lok Sabha; 543 elected seats today.

Short trick: Max now 530 + 20 = 550 (552 only before 2020).

Concept: Recall each Article.

1. Art 50 (DPSP) – separation of judiciary from executive → a-II.
2. Art 143 – President may seek the Supreme Court's advisory opinion → b-IV.
3. Art 61 – procedure for impeachment of the President → c-I.
4. Art 320 – functions of Public Service Commissions → d-III.

Short trick: Only option A has a-II and b-IV.

Concept: First check whether the Zener is ON; if ON, the load voltage is clamped at $V_Z$ and $I_Z=I_S-I_L$.

1. Without Zener: $V_L=120\times \frac{10}{15}=80$ V > 50 V, so the Zener conducts and $V_L=50$ V.
2. Series current $I_S=\frac{120-50}{5\mathrm{k}\mathrm{\Omega }}=14$ mA.
3. Load current $I_L=\frac{50}{10\mathrm{k}\mathrm{\Omega }}=5$ mA.
4. $I_Z=14-5=9$ mA.

Short trick: $I_Z=I_S-I_L$; 14 mA (option D) is the trap – that is the series current.

Concept: CE amplifier gives high current gain ($\beta$) and high voltage gain, hence the highest power gain; it is the standard voltage amplifier.

1. CE: $A_v=-\beta R_C/r_{in}$ – large (hundreds).
2. CB: current gain $\alpha <1$, very low input impedance – used for impedance matching / high frequency.
3. CC (emitter follower): $A_v\approx 1$, so it is the lowest.

Short trick: CE = ‘everything high’ (voltage, current, power gain); CC = voltage gain ≈ 1.

Concept: In GaAs (III–V), a dopant with one electron fewer than the atom it replaces is an acceptor.

1. Cd (group II, 2 valence e⁻) replaces Ga (group III) → one electron short → acceptor → p-type.
2. Se, Te (group VI) replace As (group V) → extra electron → n-type.
3. Si (group IV) is amphoteric; in GaAs it mostly sits on Ga sites → n-type.

Short trick: Group II on Ga site = p (Zn, Cd, Be, Mg); Group VI on As site = n (S, Se, Te).

Concept: CMRR $=20{\log }_{10}(A_d/A_{cm})$; ideal op-amp has infinite CMRR, practical good op-amps have about 90–120 dB.

1. 20–60 dB is poor (a simple discrete differential stage).
2. IC 741 ≈ 90 dB; precision op-amps ≈ 120 dB ($A_d/A_{cm}\approx {10}^6$).
3. 200 dB (${10}^{10}$) is unrealistic.

Short trick: Good op-amp CMRR ≈ 100–120 dB.

Concept: Basic gates implement the three Boolean operations.

1. AND: $Y=A\cdot B$ → Boolean multiplication (3).
2. OR: $Y=A+B$ → Boolean addition (2).
3. NOT: $Y=\overline{A}$ → complementation (1).

Short trick: AND = ‘·’, OR = ‘+’, NOT = ‘bar’ → 3-2-1.

Concept: A photodetector converts light into an electrical signal by the photoelectric (internal or external) effect.

1. A photon with $h\nu \ge E_g$ is absorbed and lifts an electron from valence to conduction band (electron–hole pair).
2. These carriers give photocurrent (photodiode, photoconductor, PMT).
3. Thermal emission is noise (dark current), not the working principle; tunneling and magnetic interaction are irrelevant.

Short trick: Photodetector = absorb photon → excite electron → current.

Concept: A 1-to-$2^n$ DEMUX with its data input held at logic 1 behaves exactly as an $n$-to-$2^n$ decoder.

1. So (A) is true.
2. A DEMUX needs NOT gates (inverters) on the select lines in addition to AND gates; it can also be built with NAND/NOR gates alone. ‘AND gates only’ is wrong, so (R) is false.

Short trick: DEMUX + data = 1 → decoder; circuit = AND + NOT.

Concept: $n=\frac{\rho N_A}{M}$ with $M$ in kg/mol.

1. $M=197$ g/mol $=0.197$ kg/mol.
2. $n=\frac{19.32\times {10}^3\times 6.022\times {10}^{23}}{0.197}=5.9\times {10}^{28}{\mathrm{m}}^{-3}$.
3. (In per cm³ it would be $5.9\times {10}^{22}$.) None of the printed options equals $5.9\times {10}^{28}$ per m³; option A has the right mantissa but the power is short by 10, so the question is treated as a bonus.

Short trick: Metals have ~${10}^{28}$–${10}^{29}$ atoms per m³.

Concept: In an odd-A nucleus, the ground-state $J^{\pi }$ is that of the last unpaired nucleon.

1. ${}^{25}$Mg: Z = 12 (even, paired), N = 13 (odd).
2. Filling: $1s_{1/2}$(2), $1p_{3/2}$(4), $1p_{1/2}$(2) = 8; then $1d_{5/2}$ holds neutrons 9–14.
3. 13th neutron is in $1d_{5/2}$: $j=5/2$, $l=2$ → parity $(-1{)}^2=+$. So $5/2^{+}$ (also the observed value).

Short trick: Nucleon number 9–14 → $d_{5/2}$ → $5/2^{+}$.

Concept: $R=R_0{A}^{1/3}$, so $R\propto A^{1/3}$.

1. $\frac{R}{R_{Fe}}=\frac{1}{2}\Rightarrow \frac{A}{56}=\frac{1}{8}$.
2. $A=7$ → ${\mathrm{Li}}^7$.

Short trick: Half radius = one-eighth mass number.