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10TH GRADE PRACTICE

Physics Problems: Direct current, Grade 10

Laws of circuits, current operation and connections.

11 problems2 subtopics
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CONDITIONS

Problems

11
№ 106

Problem 106

Direct current: Ohm's law and resistance

A voltage of 1,2 V1{,}2\,\text{V} was applied to a steel conductor with a length of 80 cm80\,\text{cm} and a cross-section of 0,15 mm20{,}15\,\text{mm}^{2} for 1 min1\,\text{min}. Resistivity 0,12 Ohm⋅mm2/m0{,}12\,\text{Ohm}\cdot\text{mm}^{2}/\text{m}. Define resistance, current, power, work, heat and charge.

  1. (0,64 Om; 1,875 A; 2,25 Vt; 135 Dzh; 135 Dzh; 112,5 Kl)\left(0{,}64\,\text{Om};\ 1{,}875\,\text{A};\ 2{,}25\,\text{Vt};\ 135\,\text{Dzh};\ 135\,\text{Dzh};\ 112{,}5\,\text{Kl}\right)
  2. (0,32 Om; 0,9375 A; 1,125 Vt; 67,5 Dzh; 67,5 Dzh; 56,25 Kl)\left(0{,}32\,\text{Om};\ 0{,}9375\,\text{A};\ 1{,}125\,\text{Vt};\ 67{,}5\,\text{Dzh};\ 67{,}5\,\text{Dzh};\ 56{,}25\,\text{Kl}\right)
  3. (1,28 Om; 3,75 A; 4,5 Vt; 270 Dzh; 270 Dzh; 225 Kl)\left(1{,}28\,\text{Om};\ 3{,}75\,\text{A};\ 4{,}5\,\text{Vt};\ 270\,\text{Dzh};\ 270\,\text{Dzh};\ 225\,\text{Kl}\right)
  4. (6,4 Om; 18,75 A; 22,5 Vt; 1350 Dzh; 1350 Dzh; 1125 Kl)\left(6{,}4\,\text{Om};\ 18{,}75\,\text{A};\ 22{,}5\,\text{Vt};\ 1350\,\text{Dzh};\ 1350\,\text{Dzh};\ 1125\,\text{Kl}\right)
№ 107

Problem 107

Direct Current: Circuits, Operation and Power

A resistance of 7 Ohm7\,\text{Ohm} was connected to a source with an EMF of 4,5 V4{,}5\,\text{V} and an internal resistance of 2 Ohm2\,\text{Ohm} for a minute. Determine load current, voltage, power, work, heat, charge and number of electrons.

  1. (5 A; 35 V; 17,5 Vt; 1050 Dzh; 1050 Dzh; 300 Kl; 1,875⋅1021 elekfronov)\left(5\,\text{A};\ 35\,\text{V};\ 17{,}5\,\text{Vt};\ 1050\,\text{Dzh};\ 1050\,\text{Dzh};\ 300\,\text{Kl};\ 1{,}875 \cdot 10^{21}\,\text{elekfronov}\right)
  2. (0,5 A; 3,5 V; 1,75 Vt; 105 Dzh; 105 Dzh; 30 Kl; 1,875⋅1020 elekfronov)\left(0{,}5\,\text{A};\ 3{,}5\,\text{V};\ 1{,}75\,\text{Vt};\ 105\,\text{Dzh};\ 105\,\text{Dzh};\ 30\,\text{Kl};\ 1{,}875 \cdot 10^{20}\,\text{elekfronov}\right)
  3. (0,25 A; 1,75 V; 0,875 Vt; 52,5 Dzh; 52,5 Dzh; 15 Kl; 9,375⋅1019 elekfronov)\left(0{,}25\,\text{A};\ 1{,}75\,\text{V};\ 0{,}875\,\text{Vt};\ 52{,}5\,\text{Dzh};\ 52{,}5\,\text{Dzh};\ 15\,\text{Kl};\ 9{,}375 \cdot 10^{19}\,\text{elekfronov}\right)
  4. (1 A; 7 V; 3,5 Vt; 210 Dzh; 210 Dzh; 60 Kl; 3,75⋅1020 elekfronov)\left(1\,\text{A};\ 7\,\text{V};\ 3{,}5\,\text{Vt};\ 210\,\text{Dzh};\ 210\,\text{Dzh};\ 60\,\text{Kl};\ 3{,}75 \cdot 10^{20}\,\text{elekfronov}\right)
№ 108

Problem 108

Direct current: Ohm's law and resistance

The resistance of an aluminum conductor at 100 ∘C100\,^{\circ}\text{C} is 28,4 Ohm28{,}4\,\text{Ohm}. What will it be at 500 ∘C500\,^{\circ}\text{C}, if α=0,0042 K−1\alpha=0{,}0042\,\text{K}^{-1}?

  1. 124 Om124\,\text{Om}
  2. 620 Om620\,\text{Om}
  3. 62 Om62\,\text{Om}
  4. 31 Om31\,\text{Om}
№ 109

Problem 109

Direct Current: Circuits, Operation and Power

At a voltage of 3,2 V3{,}2\,\text{V}, the current in the circuit is 0,5 A0{,}5\,\text{A}, and at 2,6 V2{,}6\,\text{V} - 1 A1\,\text{A}. Determine the emf and internal resistance of the source.

  1. (1,9 V; 0,6 Om)\left(1{,}9\,\text{V};\ 0{,}6\,\text{Om}\right)
  2. (7,6 V; 2,4 Om)\left(7{,}6\,\text{V};\ 2{,}4\,\text{Om}\right)
  3. (38 V; 12 Om)\left(38\,\text{V};\ 12\,\text{Om}\right)
  4. (3,8 V; 1,2 Om)\left(3{,}8\,\text{V};\ 1{,}2\,\text{Om}\right)
№ 110

Problem 110

Direct Current: Circuits, Operation and Power

The concentration of conduction electrons in germanium at room temperature is 3⋅1019 m−33\cdot10^{19}\,\text{m}^{-3}. What proportion of the total number of atoms are conduction electrons? Density 5400 kg/m35400\,\text{kg/m}^{3}, molar mass 0,073 kg/mol0{,}073\,\text{kg/mol}.

  1. 6,76⋅10−10 dolya6{,}76 \cdot 10^{-10}\,\text{dolya}
  2. 3,38⋅10−10 dolya3{,}38 \cdot 10^{-10}\,\text{dolya}
  3. 1,352⋅10−9 dolya1{,}352 \cdot 10^{-9}\,\text{dolya}
  4. 6,76⋅10−9 dolya6{,}76 \cdot 10^{-9}\,\text{dolya}
№ 111

Problem 111

Direct Current: Circuits, Operation and Power

How much aluminum will be released per day at a current of 140 kA140\,\text{kA} and a voltage of 4 V4\,\text{V}? What is the energy consumption? Electrochemical equivalent 0,093⋅10−6 kg/C0{,}093\cdot10^{-6}\,\text{kg/C}.

  1. (11250 kg; 4,84⋅1011 Dzh)\left(11250\,\text{kg};\ 4{,}84 \cdot 10^{11}\,\text{Dzh}\right)
  2. (1125 kg; 4,84⋅1010 Dzh)\left(1125\,\text{kg};\ 4{,}84 \cdot 10^{10}\,\text{Dzh}\right)
  3. (562,5 kg; 2,42⋅1010 Dzh)\left(562{,}5\,\text{kg};\ 2{,}42 \cdot 10^{10}\,\text{Dzh}\right)
  4. (2250 kg; 9,68⋅1010 Dzh)\left(2250\,\text{kg};\ 9{,}68 \cdot 10^{10}\,\text{Dzh}\right)
№ 112

Problem 112

Direct Current: Circuits, Operation and Power

A 6 V6\,\text{V} voltmeter has an internal resistance of 600 Ohm600\,\text{Ohm}. How to expand the measurement limit to 30 V30\,\text{V}?

  1. 4800 Om4800\,\text{Om}
  2. 24000 Om24000\,\text{Om}
  3. 2400 Om2400\,\text{Om}
  4. 1200 Om1200\,\text{Om}
№ 113

Problem 113

Direct Current: Circuits, Operation and Power

The ammeter is designed for 2 A2\,\text{A} and has an internal resistance of 0,4 Ohm0{,}4\,\text{Ohm}. How to expand the measurement limit to 10 A10\,\text{A}?

  1. 0,05 Om0{,}05\,\text{Om}
  2. 0,2 Om0{,}2\,\text{Om}
  3. 1 Om1\,\text{Om}
  4. 0,1 Om0{,}1\,\text{Om}
№ 114

Problem 114

Direct Current: Circuits, Operation and Power

The crane motor operates at a voltage of 380 V380\,\text{V} and a current of 40 A40\,\text{A}. How long will it take him to lift a load of mass 2 t2\,\text{t} to a height of 5 m5\,\text{m} with an efficiency of 80%80\%?

  1. 8 s8\,\text{s}
  2. 4 s4\,\text{s}
  3. 16 s16\,\text{s}
  4. 80 s80\,\text{s}
№ 115

Problem 115

Direct Current: Circuits, Operation and Power

A light bulb 30 W30\,\text{W}, 40 V40\,\text{V} needs to be connected to a network 220 V220\,\text{V}. What additional resistance should be connected in series?

  1. 2400 Om2400\,\text{Om}
  2. 240 Om240\,\text{Om}
  3. 120 Om120\,\text{Om}
  4. 480 Om480\,\text{Om}
№ 116

Problem 116

Direct Current: Circuits, Operation and Power

It is necessary to manufacture a heater with a power of 600 W600\,\text{W} for a voltage of 220 V220\,\text{V}. What length of nichrome wire with cross section 0,3 mm20{,}3\,\text{mm}^{2} is needed at ρ=1,1 Ohm⋅mm2/m\rho=1{,}1\,\text{Ohm}\cdot\text{mm}^{2}/\text{m}?

  1. 44 m44\,\text{m}
  2. 220 m220\,\text{m}
  3. 22 m22\,\text{m}
  4. 11 m11\,\text{m}

THEORY

Lessons on the topic

Current, resistance and Ohm's lawCurrent strength and density, resistance, emf and Ohm's law.Current work and electrical circuitsWork, power, heat, electrolysis and resistor connections.

DIRECTORY

Formulas by topic

Efficiencyη · %PowerP, N · WWorkA · JElectrical resistanceR · OhmResistivityρ · Ohm mElectromotive forceε · B