TextBook Solutions
- A battery of 9 V is connected in series with resistors of 0.2 Ω, 0.3 Ω, 0.4 Ω, 0.5 Ω and 12 Ω, respectively There is no current division occurring in a series circuit. Current flow through the component is the same, given by Ohm’s law as V= IR I= V... 1
- When a 12 V battery is connected across an unknown resistor, there is a current of 2.5 mA in the circuit. Resistance (R) of a resistor is given by Ohm's law as,V= IR R= V/I Where, Potential difference, V= 12 V Current in the circuit, I= 2.5 mA =... 1
- A copper wire has diameter 0.5 mm and resistivity of 1.6 × 10−8 Ω m. What will be the length of this wire to make https://youtu.be/gdC4O4SbCAg 2
- How is a voltmeter connected in the circuit to measure the potential difference between two points? To measure the potential difference between two points, a voltmeter should be connected in parallel to the points. 1
- Two conducting wires of the same material and of equal lengths and equal diameters are first connected in series and Correct option is c) 1:4 2
- An electric bulb is rated 220 V and 100 W. When it is operated on 110 V, the power consumed will be - (a) 100 W Correct option is d) 25 W 2
- Which of the following terms does not represent electrical power in a circuit? (a) I2R (b) IR2 (c) VI (d) V2/R Correct option is b) IR² 2
- A piece of wire of resistance R is cut into five equal parts. These parts are then connected in parallel. Correct option is d) 25 2
- An electric motor takes 5 A from a 220 V line. Determine the power of the motor and the energy consumed in 2 h. Power (P) is given by the expression,P = VI Where, Voltage,V = 220 V Current, I = 5 A P= 220 x 5 = 1100 W Energy consumed by the motor = Pt... 1
- What determines the rate at which energy is delivered by a current? The rate of consumption of electric energy in an electric appliance is called electric power. Hence, the rate at which energy is delivered b... 1
- An electric iron of resistance 20 Ω takes a current of 5 A. Calculate the heat developed in 30 s The amount of heat (H) produced is given by the joule's law of heating asH= Vlt Where, Current, I = 5 A Time, t = 30 s Voltage, V = Current... 1
- Compute the heat generated while transferring 96000 coulomb of charge in one hour through a potential difference of 50 V Given Charge, Q = 96000C Time, t= 1hr = 60 x 60= 3600s Potential difference, V= 50volts Now we know that H= VIt So we have to calculate I fi... 1
- Why does the cord of an electric heater not glow while the heating element does? The heating element of the heater is made up of alloy which has very high resistance so when current flows through the heating element, it b... 1
- What is (a) the highest, (b) the lowest total resistance that can be secured by combinations of four coils of resistance There are four coils of resistances 4 Ω, 8 Ω, 12 Ω and 24 Ω respectively. (a) If these coils are connected in series, then the equivalent re... 1
- How can three resistors of resistances 2 Ω, 3 Ω and 6 Ω be connected to give a total resistance of (a) 4 Ω, (b) 1 Ω? https://youtu.be/4fV86enlX04 2
- What are the advantages of connecting electrical devices in parallel with the battery instead of connecting them in seri There is no division of voltage among the appliances when connected in parallel. The potential difference across each appliance is equal to... 1
- An electric lamp of 100 Ω, a toaster of resistance 50 Ω, and a water filter of resistance 500 Ω are connected https://youtu.be/MyGgXsAxodg 2
- Judge the equivalent resistance when the following are connected in parallel − (a) 1 Ω and 106Ω, (b) 1 Ω and 103Ω and (a) When 1 Ω and 10⁶ Ω are connected in parallel: Let R be the equivalent resistance. therefore 1/R = 1/1+1/10⁶ \\ R=10⁶/1+10⁶ simeq 10⁶/10⁶... 1
- Redraw the circuit of question 1, putting in an ammeter to measure the current through the resistors and a voltmeter to An ammeter should be connected in the circuit in series with the resistors. To measure the potential difference across the resistor it shoul... 1
- Draw a schematic diagram of a circuit consisting of a battery of three cells of 2 V each, a 5 Ω resistor Three cells of potential 2 V, each connected in series therefore the potential difference of the battery will be 2 V + 2 V + 2 V = 6V. The f... 1
- Use the data in Table 12.2 to answer the following - Table 12.2 Electrical resistivity of some substances at 20°C (a) Resistivity of iron = 10.0 x 10⁻⁸ Ω Resistivity of mercury = 94.0 x 10⁻⁸ Ω Resistivity of mercury is more than that of iron. This implie... 1
- Why are coils of electric toasters and electric irons made of an alloy rather than a pure metal? The resistivity of an alloy is higher than the pure metal. Moreover, at high temperatures, the alloys do not melt readily. Hence, the coils... 1
- Let the resistance of an electrical component remains constant while the potential difference across According to Ohm’s law V = IR ⇒ I=V/R ... (1) Now Potential difference is decreased to half ∴ New potential difference Vʹ=V/2 Resistance rem... 1
- Will current flow more easily through a thick wire or a thin wire of the same material, when connected to the The current will flow more easily through thick wire. It is because the resistance of a conductor is inversely proportional to its area of c... 1