Doubtly
@Doubtly · Joined Feb 2021
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- Relation between voltage, current and resistance is given by R=V/I Measured value of voltage (50 ±2) volt, measured value of current is (20 ±2)A. Answer: 14% For R = V/I , the maximum relative error is the sum of the relative errors: Δ R/R = Δ V/V + Δ I/I Here V = 50 V, Δ V = 2 V, I =... 1
- Relation between energy density of electric field (UE) and magnetic field (UB) will be: correct answer is 3) U_E=U_(B ) Average energy density of electric field and magnetic field are same. 1
- A common transistor radio set requires 12V (D.C.) for its operation. The D.C. source is constructed by using a transformer The correct answer is 440 N_pover N_s=V_pover V_s N_pover24=220over12 N_p=200×24over12 N_p=440 1
- The coefficient of static friction between a wooden block of mass 0.5 kg and a vertical rough wall is 0.2. the correct answer is 25 N Given:: μ_s = 0.2 Solution:: m=0.5 kg g=10 m/s² We know that f_s= μ N To keep the block adhere to the wall here N... 1
- An audio signal υm = 20sin2π(1500t) amplitude modulates a carrier υc =80 sin 2π (100,000t). The value of percent modulation is ________. Correct answer is 25 v_m = 20 sin [100π t+πover4] :v_c = 80 sin [10⁴π t+πover6] we know that, modulation index = A_mover A_c from given equa... 1
- A resonance circuit having inductance and resistance 2 × 10–4 H and 6.28 Ω respectively oscillates at 10 MHz frequency. correct answer is 2000 R = 6.28 Ω f = 10 MHz L = 2 × 10⁻⁴ Henry We know that quality factor Q is given by ⇒ Q = X_L / R = ωL / R also, ω = 2... 1
- Each side of a box made of metal sheet in cubic shape is ‘a’ at room temperature ‘T’, the coefficient of linear expansion of the metal sheet is ‘α’. The correct Answer is C) 3a³αΔT ΔV = VγΔT ΔV = 3a³αΔT 2
- The work done by a gas molecule in an isolated system is given by, W = α.β2.e-x2 / αkT, where x is the displacement, k is the Boltzmann constant and T is the The correct option is c) MLT^(-2 ) we knnow that ,x² / α.k.T = dimensionless [x² / α.k.T ] = [M⁰L⁰T⁰] [α] = [L² / k.T] ⇒ [κ] = [M¹L²T⁻²K⁻¹]... 1
- The focal length f is related to the radius of curvature r of the spherical convex mirror by: The correct Answer is B) f = +½ r Explaination : So, r / 2 = f f = +½ r 1
- A current through a wire depends on time as i = α0t + βt2 where α0 = 20 A/s and β = 8 As-2. Find the charge crossed through a section of the wire in 15 s. Correct Answer is B) 11250 C Explaination :: we have , i = α₀t + βt² , α = 20 A/s and β = 8As⁻² ,t = 15 sec We know that , i= dqover dt⇒ ∫₀^... 1
- Statement-I: Two photons having equal linear momenta have equal wavelengths. Statement-II: If the wavelength of a photon is decreased, Correct option is d) Statement-I is true but Statement-II is false Energy of photon E = hc / λ = E ∝ 1 / λ Hence, energy of photon increases... 1
- Consider two satellites S1 and S2 with periods of revolution 1 hr and 8 hr respectively revolving around a planet in circular orbits. The correct answer is A) 8:1 we have formula , ω = 2over T given the, ratio of time period T₁over T₂=1over8 from formula, ω ∝ 1over T ω₁ ove... 1
- Four identical particles of equal masses 1 kg made to move along the circumference of a circle of radius 1 m under the action of their own mutual gravitational The correct option is A) space√( (1+2sqrt2)Gspace over2) explaination:: By resolving force F₂, we get F₁ + F₂ cos 45° + F₂ cos 45° = F_c F₁... 2
- The integral int (2x^12+5x^9 /(x^5+x^3+x)^3) dx is equal to The correct answer is x¹⁰over 2(x⁵+x³+1)²+C Explanation :: 1
- A gas contained in a cylinder fitted with a frictionless piston expands against a constant external pressure of 1 atm from triangle V =10-5=5 space litre=5×10³ m³ Q=400J space ,space space P=1atm =1.013×10⁻⁵ pa W=p.dV= 1.013×10⁵ ×5 ×10⁻³ =506.5 J triangle U=Q-W =... 1
- How many chain isomers are possible in C5H12 , answer 3 isomers are possible explaination:: Pentane (C₅H₁₂)is an organic compound with five carbon atoms. Pentane has three structural isomers tha... 1
- The empirical formula of a gaseous compound is CH2 .The density of the compound is 1.25 gm/lit.at S.T.P. The correct option is A) C₂H_(4 ) _(explaination: ) _(Since, 1 lite contains 1.25 gms. Hence 22.4 litres contain(1.25×22.4)gms≡28gms. So mol... 1
- Which of the following is a tautology ? A) (∼p)∧(p∨q)→q option 1) is correct ∼p∧(p∨q)→q (∼p∧p)∨(∼p∧q)→q C∨(∼p∧q)→q (∼p∧q)→q ∼(∼p∧q)∨q =(p∨∼q)∨q=p∨t=t 1