Q14.A direct current of 4 A and an alternating current of peak value 4 A flow through resistance of 3 Ω and 2 Ω respectively. The ratio of heat produced in the two resistances in same interval of time will be : (1) 3 : 2 (2) 3 : 1 (3) 3 : 4 (4) 4 : 3
What This Question Tests
This question evaluates the understanding of heat generation by both DC and AC currents, requiring the use of the RMS value for alternating current calculations.
Concepts Tested
Formulas Used
H = I²Rt
I_rms = I_peak / √2
📚 NCERT Sections This Tests
7.3 — Representation Of Ac Current And Voltage
Physics Class 11 · Chapter 7
7.3 REPRESENTATION OF AC CURRENT AND VOLTAGE BY ROTATING VECTORS — PHASORS In the previous section, we learnt that the current through a resistor is in phase with the ac voltage. But this is not so in the case of an inductor, a capacitor or a combination of these circuit elements. In order to show phase relationship between voltage and current in an ac circuit, we use the notion of phasors. The analysis of an ac circuit is facilitated by the use of a phasor diagram. A phasor* is a vector which rotates about the origin with angular speed w, as shown in Fig. 7.4. The vertical components of phasors V and I represent the sinusoidally varying quantities v and i. The magnitudes of phasors V and I represent the amplitudes or the peak values vm and im of these oscillating quantities. Figure 7.4(a) shows the FIGURE 7.4 (a) A phasor diagram for the voltage and current phasors and their circuit in Fig 7.1. (b) Graph of v and i versus wt.relationship at time t1 for the case of an ac source connected to a resistor i.e., corresponding to the circuit shown in Fig. 7.1. The projection of voltage and current phasors on vertical axis, i.e., vm sinwt and im sinwt, respectively represent the value of voltage and current at that instant. As they rotate with frequency w, curves in Fig. 7.4(b) are generated. From Fig. 7.4(a) we see that phasors V and I for the case of a resistor are in the same direction. This is so for all times. This means that the phase angle between the voltage and the current is zero.
4.10 — Two Moving Coil Meters, M1 And M2 Have The Following Particulars:
Physics Class 11 · Chapter 4
4.10 Two moving coil meters, M1 and M2 have the following particulars: R1 = 10 Ω, N1 = 30, A1 = 3.6 × 10–3 m2, B1 = 0.25 T R2 = 14 Ω, N2 = 42, A2 = 1.8 × 10–3 m2, B2 = 0.50 T (The spring constants are identical for the two meters). Determine the ratio of (a) current sensitivity and (b) voltage sensitivity of M2 and M1.
3.2 — A Battery Of Emf 10 V And Internal Resistance 3 Ω Is Connected To A
Physics Class 11 · Chapter 3
3.2 A battery of emf 10 V and internal resistance 3 Ω is connected to a resistor. If the current in the circuit is 0.5 A, what is the resistance of the resistor? What is the terminal voltage of the battery when the circuit is closed?
📋 Question Details
- Chapter
- AC Circuits
- Topic
- Heat produced by AC and DC
- Year
- 2022
- Shift
- 27 Jul Shift 1
- Q Number
- Q14
- Type
- MCQ
- NCERT Ref
- Class 12 Physics Ch 7: Alternating Current
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