4. HP2/ENG/TZO/XX Electrical resistors can be made by forming a thin film of carbon on a layer of an insulating material
Posted: Thu Apr 28, 2022 9:04 am
Could someone explain why aii is incorrect? The marcksheme only
multiplies the power (1500W) times the area of one face of the
resistor, but not all, and I don´t understand why. Attached is a
picture of the marcksheme.
4. HP2/ENG/TZO/XX Electrical resistors can be made by forming a thin film of carbon on a layer of an insulating material. (a) A carbon film resistor is made from a film of width 8.0 mm and of thickness 2.0 um. The diagram shows the direction of charge flow through the resistor. resistor 8.0 mm charge flow 12.0 um not to scale (0) The resistance of the carbon film is 8292. The resistivity of carbon is 4.1x10 m. Calculate the length 1 of the film. [1] Р- RA Un no$:ö [82/(2*6*22.415) ...G..03.2m. (ii) The film must dissipate a power less than 1500 W from each square metre of its surface to avoid damage. Calculate the maximum allowable current for the resistor. 7 [2] -3 _3 6 2 .*: Pries.3.14576x1095 0.037 1500x{8410*20.032)2 x (8 110° x 2410) 2 a favök 0 413) * : ........ I = (BA) 1.6.2008 (. A : R
a a ii power = 1500 x 8 x 10-20.032 «=0.384>> ( «current power resistance 0.384 82 0.068 «A»
multiplies the power (1500W) times the area of one face of the
resistor, but not all, and I don´t understand why. Attached is a
picture of the marcksheme.
4. HP2/ENG/TZO/XX Electrical resistors can be made by forming a thin film of carbon on a layer of an insulating material. (a) A carbon film resistor is made from a film of width 8.0 mm and of thickness 2.0 um. The diagram shows the direction of charge flow through the resistor. resistor 8.0 mm charge flow 12.0 um not to scale (0) The resistance of the carbon film is 8292. The resistivity of carbon is 4.1x10 m. Calculate the length 1 of the film. [1] Р- RA Un no$:ö [82/(2*6*22.415) ...G..03.2m. (ii) The film must dissipate a power less than 1500 W from each square metre of its surface to avoid damage. Calculate the maximum allowable current for the resistor. 7 [2] -3 _3 6 2 .*: Pries.3.14576x1095 0.037 1500x{8410*20.032)2 x (8 110° x 2410) 2 a favök 0 413) * : ........ I = (BA) 1.6.2008 (. A : R
a a ii power = 1500 x 8 x 10-20.032 «=0.384>> ( «current power resistance 0.384 82 0.068 «A»