Join WhatsApp Icon JEE WhatsApp Group
Question 21

A transformer consisting of 300 turns in the primary and 150 turns in the secondary gives output power of 2.2 kW. If the current in the secondary coil is 10 A, then the input voltage and current in the primary coil are:

We have a transformer with $$N_p = 300$$ turns in the primary winding and $$N_s = 150$$ turns in the secondary winding. For an ideal transformer, the voltage ratio is given by the basic transformer turns-ratio formula

$$\frac{V_s}{V_p} = \frac{N_s}{N_p}.$$

Here $$V_p$$ is the primary (input) voltage and $$V_s$$ is the secondary (output) voltage. Substituting the given numbers, we get

$$\frac{V_s}{V_p} = \frac{150}{300} = \frac12.$$

So the secondary voltage is precisely one-half of the primary voltage:

$$V_s = \frac12\,V_p \quad\Longrightarrow\quad V_p = 2\,V_s.$$

Now, the question supplies the output power of the transformer as $$P_{\text{out}} = 2.2\ \text{kW} = 2200\ \text{W}$$ and also tells us that the current in the secondary coil is $$I_s = 10\ \text{A}.$$ Using the definition of electrical power,

$$P_{\text{out}} = V_s I_s,$$

we can determine the secondary voltage:

$$V_s = \frac{P_{\text{out}}}{I_s} = \frac{2200\ \text{W}}{10\ \text{A}} = 220\ \text{V}.$$

With $$V_s = 220\ \text{V}$$ already in hand and the earlier relation $$V_p = 2\,V_s,$$ we immediately obtain the primary voltage:

$$V_p = 2 \times 220\ \text{V} = 440\ \text{V}.$$

For an ideal transformer (neglecting losses), the input power equals the output power:

$$P_{\text{in}} = P_{\text{out}}.$$

Therefore, $$P_{\text{in}} = V_p I_p,$$ where $$I_p$$ is the primary current. Substituting the known values,

$$V_p I_p = P_{\text{out}} \quad\Longrightarrow\quad 440\ \text{V}\, \times I_p = 2200\ \text{W}.$$

Solving for $$I_p$$ gives

$$I_p = \frac{2200\ \text{W}}{440\ \text{V}} = 5\ \text{A}.$$

So the transformer must be supplied with $$440\ \text{V}$$ and will draw $$5\ \text{A}$$ from the primary source.

Hence, the correct answer is Option C.

Get AI Help

Create a FREE account and get:

  • Free JEE Mains Previous Papers PDF
  • Take JEE Mains paper tests

JEE Quant Questions | JEE Quantitative Ability

JEE DILR Questions | LRDI Questions For JEE

JEE Verbal Ability Questions | VARC Questions For JEE

Free JEE Topicwise Questions

JEE Rotational MotionJEE Units & MeasurementsJEE Atomic StructureJEE GravitationJEE Periodic Table & PeriodicityJEE StatisticsJEE Inverse Trigonometric FunctionsJEE Magnetism & Magnetic MaterialsJEE Sequences & SeriesJEE MatricesJEE Alternating CurrentsJEE Carboxylic AcidsJEE Permutations & CombinationsJEE Work, Energy & PowerJEE Electromagnetic InductionJEE Electronic DevicesJEE d and f-Block ElementsJEE Chemical KineticsJEE Heat TransferJEE Three Dimensional GeometryJEE Magnetic Effects of CurrentJEE Hydrocarbons - AromaticJEE Electromagnetic WavesJEE Aldehydes & KetonesJEE Hydrocarbons - AlkanesJEE Applications of DerivativesJEE EquilibriumJEE Indefinite IntegrationJEE Chemical ThermodynamicsJEE ElectrochemistryJEE ProbabilityJEE BiomoleculesJEE Continuity & DifferentiabilityJEE Kinetic Theory of GasesJEE Vector AlgebraJEE Hydrocarbons - AlkynesJEE Differential EquationsJEE Current & ResistanceJEE Straight LinesJEE WavesJEE Redox ReactionsJEE Hydrocarbons - AlkenesJEE DeterminantsJEE SolutionsJEE Ray OpticsJEE Dual Nature of Matter & RadiationJEE Chemical Bonding & Molecular StructureJEE Complex NumbersJEE Sets, Relations & FunctionsJEE Electric Charges & FieldsJEE Laws of MotionJEE Fluid MechanicsJEE Basic Concepts in ChemistryJEE Trigonometric FunctionsJEE LimitsJEE Laws of ThermodynamicsJEE Kinematics - 2D MotionJEE p-Block Elements (Groups 13-18)JEE Simple Harmonic MotionJEE Electric Potential & CapacitanceJEE Coordination CompoundsJEE JEE 2D GeometryJEE CirclesJEE Definite IntegrationJEE EMF & Circuit AnalysisJEE Surface TensionJEE Atoms & NucleiJEE Laboratory Experiments - XIJEE Number SystemJEE Basic Principles of Organic ChemistryJEE Wave OpticsJEE Quadratic EquationsJEE Alcohols, Phenols & EthersJEE Organic Compounds with HalogensJEE DifferentiationJEE Conic SectionsJEE Nitrogen-Containing CompoundsJEE ElasticityJEE Practical Organic ChemistryJEE Kinematics - 1D MotionJEE Purification & CharacterisationJEE Binomial Theorem
Ask AI