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When is more power delivered to a light ...

When is more power delivered to a light bulb, just after it is turned on and the glow of the filament is increasing or after it has been ON for a few seconds and the glow is steady?

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To determine when more power is delivered to a light bulb, we need to analyze the behavior of the filament when the bulb is first turned on versus after it has been on for a few seconds. ### Step-by-Step Solution: 1. **Initial Condition**: When the light bulb is first turned on, the filament is cold. At this stage, the resistance of the filament is low. **Hint**: Remember that resistance in a filament changes with temperature. ...
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(a) what is the rate at which energy being delivered to a light bulb higher : just after it is turned on , the glow of the filament is increasing , or after it has been on for a few seconds and the glow is steady ? (b) IF a piece of wire is used to connect points b and c in Fig. 7.9, does the brightness of bulb R_(1) increase , decrease or stay constant ? What happens to the brightness of bulb R_(2) ? (I_(1) = I_(2) = I) (c) Compare the brightness of four identical light bulbs in Fig. 7.10 . What happens if the bulb A fails so that it cannot conduct ? What if C fails ? What if D fails? (d) If electric power is transmitted over long distances, the resistance of the wires becomes significant. Why ? Which mode of transmission would result in less energy losss: high current and low voltage or low current and high voltage ? Discuss. (e) In Fig. 7.11 , describe wha happens to the light bulb after the switch is closed . Assume the capacitor has a large capacitance and is initially uncharged. (f) Astuident claims that a second light bulb in series is less bright than the first , because the first bulb uses up some of the current . How would you respond to this statement ? (g) If you were to design an electeric heater using nichrome wire as the heating element , what parameters of the wire would you vary to meet a specific power output , sch as 1000 W ?

Find the current through the battery (i) just after the switch is closed. (ii) long after the switch has been closed.

Knowledge Check

  • The resistance of wire in a heater at room temperature is 65Oemga . When the heater is connected to a 220V supply the current settles after a few seconds to 2.8A. What is the steady temperature of the wire. (Temperature coefficient of resistance alpha=1.70xx10^(-4) ^(@).C^(-) )

    A
    `955^(@)C`
    B
    `1055^(@)C`
    C
    `1155^(@)C`
    D
    `1258^(@)C`

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